DE1668876B2 - N-ACYL PROTECTED AMINO ACIDS AND PEPTIDES, THE PROCESS FOR THEIR PRODUCTION AND THEIR USE IN PEPTIDE SYNTHESIS - Google Patents

Description

Ac-NH-A

wherein -NH-A is the residue of an amino acid or a peptide, or a derivative of these compounds, means and Ac the group

1·

R ₇ -CO-CO-

25th

R ₂ -CO-CO-

is, in which R, for _{lower alkyl with at most 5 carbon atoms, R 2} for lower ralkyl with at most 5 carbon atoms or phenyl and R3 for phenyl and in which the phenyl radicals are unsubstituted or by one or two lower alkyl groups with at most 5 carbon atoms, phenyl groups or lower alkylphenyl groups with the highest 5 carbon atoms are substituted in the lower alkyl radical.

2. N-acyl-protected amino acids and peptides and their derivatives of the general formula 1, in which Ac means the 2-phenyl-2-propyloxycarbonyl group.

3. N-acyl-protected amino acids and peptides and their derivatives of the general formula I. wherein denotes the 2- (p-Bi-phenylyl-2-propyloxycarbonyl group.

4. N-acyl-protected amino acids and peptides and their derivatives of the general formula I, in which Ac means the 2-p-tolyl-2-propyloxycarbonyl group.

5. Process for the preparation of the N-acyl-protected amino acids and peptides and their Derivatives according to Claims 1 to 4, characterized in that the protective group

¹ st

R ₂ -CO-CO-

R ₃

wherein Ri, R ₂ and R3 have the meaning given in claims 1 to 4, introduces amino acids or peptides or their derivatives in a manner known per se.

b. Use of the compounds according to Claims 1 to 4 for peptide synthesis.

35

40

The present invention is concerned with the temporary protection of amino groups in dtide syntheses by acylation of the amino group, subsequent cleavage of the introduced acyl lip. In particular, the subject matter is in which Ri stands for lower alkyls with at most 5 carbon atoms, R ₂ for lower alkyls with at most 5 carbon atoms or phenyl and R ₃ for phenyl and in which the phenyl radicals are unsubstituted or by one or two lower alkyl groups with at most 5 carbon atoms, phenyl groups or lower alkylphenyl groups with at most 5 carbon atoms in the lower alkyl radical are substituted, as well as processes for the preparation of these compounds and their use in the synthesis of peptides. The substituents on the phenyl radicals are mainly in the para position; they can also be in the ortho or ortho and para position. The lower alkyl are primarily methyl or ethyl, also z. B. propyl or butyl. The lower alkyl groups are straight-chain, but can also - especially in the case of the phenyl substituents - be branched.

It is known that in the synthesis of peptides by coupling of amino acids or peptides in the generally the functional groups not involved in the coupling reaction, for example the terminal amino or terminal carboxyl group, the amino and carboxyl groups of the side chains and optionally other groups, such as mercapto, guanidino or hydroxyl groups, are blocked. It Although a larger number of protective groups are available today, they are not yet fully capable to satisfy, especially when it comes to that Synthesis of long-chain and sensitive peptides. The main problem is that in In such cases, hydrogenolytic cleavage is often not possible (because of the presence of sulfur-containing Amino acids) and that the peptides compared to hydrolytically acting acidic or especially alkaline Agents are not stable enough so that the huirolytic Cleavage of all protective groups in the last stage of the synthesis with great losses Material is connected.

Another difficulty is that the am The protective group located at the end of the coupling must be split off after each coupling reaction, while the other protective groups are to be retained until the end of the synthesis. These two A.rteit protective groups must therefore on the one hand be selectively removable from one another, but on the other hand both species must be able to be removed under mild conditions.

As cleavable under mildly acidic conditions side-chain protecting groups have especially the tert-butyloxycarbonyl (BOC) Gi "uppe to protect the amino groups and ^d: e lert.-butyl ester (tBu) group proved to protect the carboxyl group; in addition there is the tertiary Builher group for the protection of

u Hroxv groups. In addition to these groups, the Keruppe, z. For example, as "amino protecting group, are rf red selective because it is faster cleavable in weakly acidic medium very • \, for example, in 80% äwe at room temperature 20 OOOinal faster. but the applicability of the trityl group as hppe is very limited because of steric

ivfer, however, is the Anw r iygpp

Amino protecting group very limited. Be due to steric hindrance, it may f in the coupling according to the activated ester method and the mixed anhydride used ht • (except for glycine), and executes ⁿ 'h in the carbodiimide to poor Xeuten. It therefore comes from the carboxyl end in the synthesis of p ^ tides, e.g. B. not the new methods of solid support synthesis (cf. Merrif eld J Am. Chem. Soc. 85, 2149 [1963]) not in use. The trityl group as an amino protective group has disadvantages because it is difficult to introduce and the trityl-protected compounds

«And not very stable.
It has now been found that protecting groups of

general formula

!
R ₂ -CO-CO-

IO

IS

20th

where Ri, R2 and R _{3 have} the meanings given at the beginning, advantageous in the synthesis of long-chain sensitive peptides and superior to known protective groups, such as the trityl group

are.
Particularly noteworthy are the 2-phenyl-2-pro-

pyloxycarbonyl, 2-p-biphenylyl-2-propyloxycarbonyl and 2-p-tolyl-2-propyloxycarbonyl groups which represent the desired advantageous properties, such as selectivity in the event of cleavage and good accessibility, in one have particularly favorable dimensions.

The new groups are distinguished by the fact that they can operate under very mild acidic conditions, e.g. B. at room temperature in about 60-90% aqueous acetic acid, chloroacetic acid or formic acid or a mixture of at least two of these acids with 10-40% water. _4S

The advantageous properties of the new protective group cleavage under very mild acidic conditions, selective cleavage with respect to other acidolytically cleavable protective groups, especially those of the "tert-butyl type", can be demonstrated by comparing the cleavage rates under mild acidic conditions. As from the publication by Sieber and 1 se 1 i η, HeIv. Chim. Acta 51 (1968) p. 614 (in particular Table 1, p. 616), the protecting groups of the invention, namely the 2-phenyl-2-propyloxycarbonyl, 2-p-biphenylyl-2-propyloxycarbonyl, 2-p -Tolyl-2-propyloxycarbonyl, 1,1-diphenylethyl and U-diphenylpropyl groups in 80% acetic acid are split off 700 to 10000 times faster than the ( ₁₀ BOC group. These groups can therefore be split off selectively with respect to BOC. The benzyloxycarbonyl group is not split off with 80% acetic acid and even with glacial acetic acid. According to Schröder and Lübke: "The Peptides", Vol. _{it is cleaved off in 1 to 1V 2} hours with 12N hydrochloric acid at 37 ° C. The p-methoxybenzyl-oxycarbonyl group is cleaved off in 2 hours in accordance with Schröder and Liibke, IeS 35. Z. 5-6 mN boiling glacial acetic acid.

Also Su-Sun Wang and Mernfield, Int. J. Protein Research I. 235-244, have the particular suitability of the 2-biphenylyl-2-propyloxycarbonyl group (Bpoc) in the solid support synthesis of peptides highlighted. On p. 239 they write that they have to test the selectivity N-Bpoc-L-aspartic acid benzyl ester, N ^ Bpoc-O-benzyl-L-threonine and N-Bpoc-N'-benzyloxycarbonyl-L-lysine in methylene chloride containing l, 5O / o anhydrous trifluoroacetic acid Maintained room temperature. In less than lOMraitM the Bpoc group was removed from these 3 compounds, while the benzyl ester group of aspartic acid, the benzyl ether group of threonms and the Benzyloxycarbonyl group of Lys.ns were still unchanged after 100 hours.

Since the splitting-off speed of the Protecting groups is more than 600 times larger than that of the BOC group, the split off groups according to the invention with sufficient selectivity compared to the latter group, also against the tert-butyl ester group of tert, butyl ether group and the trityl mercapto protecting group. They are therefore particularly suitable as amino protective groups in the synthesis of sensitive ones Peptides, which are acid-labile chain link groups, like the groups mentioned. Since they show no steric hindrance, they stick to it any coupling method and in particular also be. of solid support synthesis.

The new groups will be introduced after an known methods, analogous to the introduction, the BOC group, for example by means of; the ^ method or the activated ester method (e.g. phenyl ester, p-nitrophenyl ester, hydroxysuccin.midester) or by reacting carbmoles of the formula

RiR ₂ R ₃ C-OH

with the isocyanate acid corresponding to the amino acids

ester.

In the following examples, the introduction and splitting off of the new groups will take place at some natural «amino acids and peptides built up from natural α-amino acids are shown. In the same The groups are also applied to other amino acids and peptides. The temperatures are given in degrees Celsius.

Example

Introduction of the 2-phenyl-isopropyloxy carbonyl group

1) 5.35 g of isocyanate acetic acid ethyl ester (41.5 mmol),

4 ml of pyridine and 5.64 g of phenyldimethylcarbinol

(41.5 mmol) are heated to 50 ° for 38 hours. the

yellow solution is taken up in 60 ml of ether, at

with 1-M citric acid and shaken out with water

dried over sodium sulfate and completely in vacuo

dig evaporated. The residue is rubbed in

Petrolather, filter off the solid substance and boil it

at reflux in 70 ml of hexane. The undissolved material is filtered off

Material off, the filtrate is reduced to half, filter

over 0.5 g of activated charcoal and leaves the N- (2-phenyl-isopro

pyloxycarbonyl) glycine ethyl ester crystallize out.

69-70 °. The product is in the thin layer chromate

gram uniform in chloroform, Rf = 0.4.

675 mg (2.55 mmol) of the ester are dissolved in 10 ml of dioxane, 1.47 ml of 1.91 N NaOH are added and the mixture is stirred at room temperature for _{2 hours.} The clear solution is diluted with 20 ml of water, extracted twice with ether, which is washed twice with a little water. The combined aqueous solutions are acidified to pH 2 with citric acid at 0 °, extracted twice with ether, washed neutral, dried and filtered. Dicyclohexylamine is now added to the ethereal solution until the alkaline reaction occurs, whereupon the salt begins to crystallize when scratched. The ethereal solution is concentrated to about 10 ml, left to crystallize for a few hours at 0 °, then the crystals of N- (2-phenylisopropyloxycarbonyO-glycine- The dicyclohexyl ammonium salt is filtered off and washed with ether, mp: 162-163 ° (with weak decomposition).

2) 60 g of phenyldimethylcabinol (0.44 mol) in 450 ml of absolute methylene chloride and i »3 ml of absolute pyridine (0.66 MoJ) are mixed with 67 ml of phenyl chlorocarbonate (0.53 mol) in 250 ml at -5 ° in 30 minutes added absolute methylene chloride. A thick suspension is created. This is stirred for a further 20 hours at 0 °, then applied to a little ice and 100 ml of methylene chloride. The methylene chloride solution obtained is washed several times with water at 0 °, dried over sodium sulfate and evaporated to dryness in vacuo at 20 °. The resulting inconsistent mixed carbonate is immediately dissolved in 180 ml of methanol, added with 52 ml of hydrazine hydrate (1.06 mol) while cooling with ice, and allowed to stand at room temperature for 20 hours. The solution is diluted with 600 ml of ether, washed at 0 ° with water, five times with 0.5 N sodium hydroxide solution and with water until neutral, dried over sodium sulfate and in vacuo at 50 °. evaporated to dryness. The residue (61 g) is distilled in a high vacuum and gives 52.1 g of 2-phenyl-isopropyloxycarbonyl-hydrazide in the form of a colorless, viscous oil. Kp .: 95-98 ° / 10 ^-3 mm Hg.

20.6 g of this hydrazide (0.106 mol) are dissolved in 320 ml of dimethylformamide and cooled to -20 ° to -30 ° and 160 ml of 1.94 N hydrochloric acid are added, the temperature being kept below -20 °. Afterward 23.2 ml of 5 M sodium nitride solution are added dropwise at -15 to -10 °. Now another 15 minutes stirred at the same temperature, then adjusted to pH 6-7 with saturated potassium carbonate solution. That The mixture is extracted with 800 and 400 ml of ether, the two ether solutions at 0 ° three times with water washed, combined, dried over sodium sulfate and evaporated to dryness in vacuo at 30 °. Of the The residue is carefully distilled in a high vacuum and 17.5 g of the azide are released as a yellowish oil Bp. 47-5Γ / 0.005 mm Hg. The IR. Spectrum shows the expected gangs. (Azide band at 4.6 and 4.7 μ S5 [split]; Carbonyl band at 5.8 μ).

2.45 g (12 mmoles) of 2-phenylisopropyloxycarbonyl azide in 14 ml of dimethylformamide with 5.75 g

N'-tert-butyloxycarbonyl-L-lysine methyl ester acetate
(18 mmol) and 2 ml of dimethylformamide were added. UNTC ^r (> o stirring is slowly added dropwise at 0 ° in 1 '/ 2 hours 4.15 ml triethylamine. The clear solution is now 3 days in the refrigerator was allowed to stand. After dilution with 50 ml of ether at 0 ° several times with 0, 1 M citric acid solution, then extracted with water until neutral, dried over sodium sulfate and evaporated to dryness. The residue is dried to constant weight in a high vacuum and forms a chromatographically uniform, viscous oil. [&]% = + & ± 0.5 ° (c = 2 in chloroform) Yield: 4.83 g = 95% of theory N * - (2-phenylisopropyloxycarbonyl) -N ^f -tert-butyloxycarbonyl-L-lysine methyl ester.

In the same way as described under 1), the para-diphenylisopropyloxycarbonyl group can be found in Introduce glycine ethyl ester. The N- (2-p-diphenylisopropyloxycarbonyl) glycine ethyl ester is obtained in this way. which crystallizes from methanol. 122 ° F.

Example 2

Introduction of the 2-p-tolyl-isopropyloxycarbonyl group

6.22 g p-tolyl-dimethylcarbinol (41.5 mmol), 4 ml absolute pyridine and 5.35 g (41.5 mmol) of ethyl isocyanate acetate are kept at 50 ° for 38 hours and worked up as described in Example 1. You get 9.8 g of Nf- (2-p-Toiyl-isopropyioxycarbony /) - glycine ethyl ester as a yellow oil; Rf = 0.25-0.35 in chloroform. For the purpose of saponification, the ester is dissolved in 100 ml of 80% strength Dissolved methanol, 24 ml of 1.9 N sodium hydroxide solution were quickly added on a pH meter, the pH being adjusted to 1.1 increases. After 7 minutes, 2N hydrochloric acid is added to pH 8.5. The resulting solution is in vacuo concentrated about half, mixed with 50 ml of water and extracted twice with ether. the Ether solutions are washed twice with water, the combined aqueous solutions at 0 ° acidified to pH 2 with citric acid and extracted with ether. The ether solution is after neutral washing, Dry with sodium sulfate and filter with dicyclohexylamine made alkaline to about 30 ml concentrated, mixed with an equal amount of petroleum ether and allowed to crystallize. 8.4 g of N- (2-p-tolyl-isopropyloxycarboxyl) -glycindicyclohexylammoni- salt from the F. 145-147 °. After recrystallization from Ethyl acetate melts the substance at 147-148 ° (u. Decomp.).

Example 3

Cleavage of the 2-phenyl-isopropyloxycarbonyl group

1) 418.6 mg of N- (2-phenylisopropyloxycarbonyl) glycine dicyclohexylammonium salt are dissolved in 4.2 ml of a mixture of 7 vol. glacial acetic acid, 1 vol. 82.8% formic acid and 2 vol. water at room temperature. After 4 Analysis by thin layer chromatography shows that about 95% has been cleaved. After 6 hours Standing at room temperature is mixed with 20 ml of acetone, the precipitated glycine is filtered off and mixed with Acetone washed well. It is clearly soluble in water and chromatographically uniform. Yield: 68.5 mg = 91.4% of theory. Under the same conditions, tert-butyloxycarboiiylglycine ethyl ester remains unchanged.

2) 71.7 mg (0.27 mmol) of N- (2-phenylisopropyloxycarbonyl) glycine ethyl ester are dissolved in 1.35 ml of 80% acetic acid at 25 ". After various times samples of 0.20 ml are taken, placed in 4 ml of dimethylformamide and treated with 0.1 n-perchloric acid titrated in glacial acetic acid (titration of the liberated glycine ethyl ester). The half-value line for the Auspal protection group takes about 2 hours. Natii 24 Hours, the split is quantitative. Even in the thin-layer chromatogram there is no: ~> pui Prove more source material. Among the same

The N-protecting group of N-tert.-butyloxycarbonyl-glycine-ethyl ester remains under conditions unchanged.

In the same way, N- (2-p-diphenylisopropyloxycarbonyl) -glycine-ethyl ester is split quantitatively _{in 3V 2 hours.}

3) 68.8 mg of N- (2-phenylisopropyloxycarbonyl) glycine ethyl ester are added to 2.6 ml of 60% chloroacetic acid Room temperature dissolved. After various times, samples of 0.20 ml are taken in 4 ml Given dimethylformamide and titrated with 0.1 n-perchloric acid in glacial acetic acid. After 15 minutes it is Connection split quantitatively. The BOC group is split off around 1900 times more slowly. In the The table below shows the cleavage rates for various acids or acidic mixtures.

Hydrolysis M edium

Quantitative
Split after

60% acetic acid
90% acetic acid
75% formic acid
Methanol 82.8% formic acid 1:
Glacial acetic acid-82.8% formic acid-water 7: 1: 2

Glacial acetic acid-82.8% formic acid-water 7: 1: 2 + sodium chloride

12 hours
50 hours
at the moment
11 hours
4 '/ 2 hours

40 minutes

IO

20th

4) 439.7 mg (1.04 mmol) of N * - (2-phenylisopropyloxycarbonyl) -N'-tert-butyloxycarbonyl-L-lysine methyl ester are dissolved in 4.4 ml of 80% acetic acid and taken for 48 hours stored at room temperature. A thin-layer chromatographic analysis after this time shows that the Ν ^Λ -protecting group is practically quantitative, the N'-tert-butyloxycarbonyl group is not split off (5. The solution is evaporated to dryness in vacuo, the residue is ^{dried in a high vacuum at 45 C} , then dissolved in a little ether, during which crystallization slowly sets in. To complete this, about the same amount of petroleum ether is added, left to stand for a few hours at 0 ° and filtered. 269 mg of crystallized N ^f -tert.-butyloxycarbonyl-L-lysine methyl ester- acetate obtained, mp 80 ° -81 ° C. The mother liquor also contains further N ^{f -tert-butyloxycarbonyllysine methyl ester.}

Example 4

Cleavage of the 2-p-tolyl-isopropyloxycarbonyl group

1) 432.6 mg (1 mmol) of N- (2-p-tolyl-isopropyloxycarbonyl ^ glyrin-dicyclohexylammonium salt are in 43 ml of a mixture of 7 vol. glacial acetic acid, 1 vol 82.8% formic acid and 2 vol water dissolved and with Stirred at room temperature. After 15 minutes and after 30 minutes, thin-layer chromatography is used Analysis carried out which shows that after 15 minutes about 95% and after 30 minutes quantitative Cleavage has occurred. Also after 30 minutes, the solution is mixed with 20 ml of acetone, briefly at 0 " left to crystallize, then the glycine is removed and washed well with acetone. Yield: 694 mg = 92.7% crystallized glycine.

2) If one uses N- (2-p-tolyl-isopropyloxycarbonyl) -glycine ethyl ester as for the corresponding 2-phenyhsopropyloxycarbonyl compound in Example 3 under 2) described treated with 80% acetic acid at 25 °, the protective group is quantitative in 1/2 hours

Example 5

Introduction of the 2-p-biphenylylisopropyloxycarbonyl group

a) with the azide into amino acid ester

106 g (0.5 mol) of p-biphenylyl-dimethylcarbinol in 500 ml of methylene chloride and 60 ml of pyridine are added in 30 minutes at -5 ° with a solution of 76 ml of phenyl chloroate in 250 ml of methylene chloride. The resulting suspension is stirred for 14 hours at 0 °, an almost clear solution being formed. This solution is evaporated to dryness at 30 ° on a rotary evaporator in vacuo and the crystalline residue consisting of 2- (biphenylyl) -isopropyloxycarbonyl-phenyl ester is dried in a high vacuum at room temperature for a further 1 hour. Then 200 ml of dimethylformamide and 125 ml of hydrazine hydrate are added and the mixture is stirred for 6 hours while cooling with cold water. The clear solution is slowly mixed with 1 liter of water while cooling with ice, left to crystallize overnight at 0 °, the crystals are filtered off and washed with 1N sodium hydroxide solution and water. After drying in vacuo at 50 °, the 2- (p-biphenylyl) isopropyloxycarbonylhydrazide is recrystallized from 200 ml of carbon tetrachloride and 40 ml of petroleum ether. 103.0 g (76% of theory) are obtained; 108-109 °.

27 g (0.1 mol) of this hydrazide are dissolved in 270 ml of acetonitrile and, while stirring at -25 °, a solution of 50 ml of 6N hydrochloric acid in 100 ml of acetonitrile and then 22 ml of 5M sodium nitrite solution are added. After stirring for 15 minutes at -15 °, the pH is adjusted to 6-7 with 2N soda solution and the solution is poured onto a lot of ice water. After brief stirring, the azide solidifies. It is filtered off and washed with ice water. The residue is dissolved in ether, the water is separated off, the ether solution is dried over sodium sulfate and the solvent is evaporated off in vacuo at room temperature. 28.3 g (100% of theory) of the azide are obtained in the form of a crystalline, yellowish powder with a melting point of 48-52 ^r .

3.37 g (20 mmol) of L-valine methyl ester hydrochloride in 10 ml of dimethylformamide under stirring at 0 ^e with 2.8 ml of triethylamine, 6.2 g of the above azide and 5 ml of dimethylformamide was added. After 10 minutes, a further 2.8 ml of triethylamine are added, and the batch is then continued overnight at room temperature . The reaction mixture is diluted with 100 ml ether, shaken out several times at 0 ° with 0.1 M citric acid solution and water, dried over Natnumsulfat and evaporated in vacuo to dryness The ester obtained is saponified directly To this end, dissolving the crude product in 75 ml of isopropanol , treated with 12 ml of 2N sodium hydroxide solution and stirred for 2V for ₂ hours at 40 °. Then ether and water are added to the solution, the aqueous solution is separated off and a second measure is added! with water. The combined aqueous solution is covered with ether, adjusted to pH 2 with 1 m citric acid at 0 ° and extracted with ether ml one, mi networked 50 ml of petroleum ether, leaving at 0 ^c crystallize. Since: crystalline product is filmed and washed with ether-petroleum ether (1: 1). 63 g of N-2- (p-Bi phenylyl / isopropytoxycarbonyl-L-valine-cydohexylammoniumsai / es with a melting point of 178-180 (decomposition) are obtained.

b) With the azide into amino acids

1.17 g of L-valine (10 mmol) are dissolved warm in 9.1 g of a 10% aqueous solution of tetramethylammonium hydroxide. The solution is evaporated in vacuo at 80 °, the residue is taken up three times in 5 ml of dimethylformamide and evaporated in vacuo. The crystalline residue is stirred with 20 ml of dimethylformamide at room temperature, 2.8 g of 2-p-biphenylyloxycarbonylazide and then 3 ml of triethylamine are added and the suspension is stirred for 1 hour at room temperature. After ether and water have been added, the aqueous solution is separated off, the ether solution is extracted twice more with a little water and the combined aqueous solutions are acidified to pH 2 ^{at 0 u.} After extraction with ether and washing neutral, the ether extracts are dried with sodium sulphate, filtered and alkalized with cyclohexylamine. The cyclohexylammonium salt begins to crystallize immediately. It is isolated in the same way as described under a). 2.96 g of N-2- (p-biphenylyl / isopropyloxycarbonyl-L-valine-cyclohexylammonium salt with a melting point of 178 ° -180 ° (decomposition) are obtained.

c) With activated ester in amino acids

1.17 g of L-valine (10 mmol) are dissolved in 4.55 ml of a 2.2 N methanolic solution of benzyltrimethylammonium hydroxide dissolved, evaporated to dryness in vacuo, redissolved in 10 ml of dimethylformamide and again evaporated in a vacuum. The residue is taken up in 5 ml of dimethylformamide with 4.0 g of 2- (p-biphenylyl) isopropyloxycarbonylphenyl ester added and stirred at 50 ° for 4 hours. The clear solution is mixed with 30 ml of water and 30 ml of ether and shaken out, the aqueous layer is separated off and acidified to pH 2 at 0 ° with citric acid. After extracting the ethereal solution is washed neutral with ether, dried, filtered and treated with 1.9 ml of cyclohexylamine offset. The cyclohexylammonium salt of N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-valine begins immediately to crystallize. It is isolated in the same way as described under a). The yield is 3.15 g: mp 178-180 ° (decomposition).

Likewise, the following N-2- (p-biphenylyl) isopropyloxycarbonyl derivatives getting produced:

derivative

F.

Glycine dicyclohexylammonium salt L-leucine
L-proline dicyclohexylammonium salt

N -tert-butyloxycarbonyl-L-lysine dicyclohexylammonium salt

L-tyrosine cyclohexylammonium salt

L-phenylalanine-dicyclohexylammonium-

L-glutamic acid-γ-tert-butyl ester cyclohexylammonium salt

L-serine tert-butyl ether cyclohexyl ammonium salt

L-methionine dicyclohexylammonum salt

192-193 °

(Decomp.)

227-230 "

(Decomp.)

173-175 °

(Decomp.)

amorphous

248-252 ° (decomp.) Sinters at 158 ° 116-119 °

(Decomp.) 174-175 »

(Dec.) 180-181 (dec.) 142-143 ^C

The 2- (p-biphenylyl) -isopropyloxycarbonyl-phenyl ester is prepared as follows:

21.2 g of p-biphenylyl-dimethylcarbonil (0.1 mol) in 100 ml of methylene chloride and 12 ml of pyridine are mixed with a solution of 18.8 g at -5 ° in 30 minutes Phenyl chlorocarbonate is added to 50 ml of methylene chloride. The mixture is then stirred for a further 18 hours 0 °, then poured onto ice water, separates the organic layer, washed several times with water, dried and the solvent evaporates in vacuo at 30 °. After recrystallization from ethyl acetate, the crystals become with Ethyl acetate-petroleum ether (2: 1) and dried in vacuo at room temperature. 25.8 g are obtained of 2- (p-biphenylyl) -isopropyloxycarbonyl-phenyl ester with a melting point of 115 ° -116 ° (decomposition).

Example 6

Cleavage of the N-2- (p-biphenylyl) -isopropyl-

oxycarronyl group from different

amino acids

90.9 mg (0.2OmMoI) N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-valine-cyclohexylammonium salt are dissolved in 2.0 ml 80% acetic acid at 25 °. After various times, samples of 0.20 ml are taken, placed in 4 ml of dimethylformamide and titrated with 0.1 n-perchloric acid in glacial acetic acid. In 3 '/ _; The protective group has been split off quantitatively for hours.

The cleavage times in 80% acetic acid are determined in the same way for the following compounds:

N-2- (p-biphenylyl) -isopropyloxycarbonyl-amino acid

Quantitative split in hours

Glycine dicyclohexylammonium salt
L-leucine

L-proline dicyclohexylammonium salt
N'-tert-butyloxycarbonyl-L-lysine dicyclohexylammonium salt
L-tyrosine cyclohexylammonium salt

L-phenylalanine dicyclohexylammonium salt

L-glutamic acid -} '- tert-butyl ester cyclohexylammonium salt
L-serine tert-butyl ether cyclohexylammonium salt

3 '/ 2
3

3-73
42/3

2> / 3

31/2
41/5

Example 7

Cleavage of the N-2- (p-biphenylyl) -isopropyl-

oxycarbonyl group from N * -2- (p-diphenyl) -

isopropyloxycarbonyl-Nt-BOC-L-lysyl-

N ⁽ -BOC-L-lysine methyl ester

a) 160.0 mg of N * -2- (p-biphenylyl) -isopropyloxycarbo

. nyl-N-BOC-L-lysyl-N'-BOC-L-lysine methyl ester who

in 22 ml of a mixture of glacial acetic acid-82.8% amei

Sense acid water (7 _{: J: 2} , parts by volume) dissolved Naci

different times are samples of 0.30 π-

taken, given in 4 ml of dimethylformamide

titrated with 0.1 N perchloric acid in glacial acetic acid

Mmuten, the! ^ Protective group has broken off quantitatively

ten, while the N ^E -BOC groups are not attacked.

b) 240 mg of the above dipeptide derivative are dissolved in 1.7 ml of methylene chloride and 1.3 ml of a solution of 37.5 g of chloroacetic acid in 12.5 ml of water are added at room temperature. After various times, samples of 0.5 ml are taken from the homogeneous solution, poured into 1.5 ml of methanol and immediately chromatographed on silica gel in the system sec-butanol-glacial acetic acid-water (67:10:23). It is found that after 15 minutes the N * protective group has been completely split off and the N ^£ -BOC groups are not attacked.

The starting material can be made as follows:

666 mg (ImMoI) N * -2- (p-biphenylyl) -isopropyloxycarbonyl-N'-BOC-lysine-dicyclohexylammonium salt in 4 ml dimethylformamide are mixed with 0.125 ml pivaloyl chloride at -15 °. After stirring at -10 ° for 15 minutes, a solution of 320 mg (ImMoI) N'-BOC-lysine methyl ester acetate in 3 ml dimethylformamide is added and the mixture is stirred at 0 ° for 2 hours. The reaction mixture is taken up in ethyl acetate, washed several times at 0 ° with 0.1 M citric acid solution, 2 N soda solution and water, then dried and evaporated to dryness in vacuo. The residue is dissolved in a little ether, whereupon rapid crystallization begins. 632 mg Ν ^Λ -2- (ρ

Biphenylyl) -isopropyloxycarbonyl-N ^F -BOC-lysyl-N ^e -BOC-lysine methyl ester with a melting point of 87-89 ° (decomposition). After recrystallization from ethyl acetate petroleum ether, the F. does not change.

Example 8

Cleavage of the N-2- (p-biphenylyl) -isopropyl-

oxycarbonyl group from N-2- (p-biphenylyl) -iso-

propyloxycarbonyl-L-propyl-L-leucyl-

L - () »- tert-butyl ester) -glutamyl-L-phenyi-

alanine tert-butyl ester

35

40

1.10 g of N-2- (p-biphenylyl) -isopropyloxycarbonyl-Pro-Leu-Glu (OtBu) -Phe-OtBu are mixed with 6.5 ml of a mixture of glacial acetic acid-82.8% formic acid-water (7: 1: 2) (vol.) _{Stirred for 2V 4} hours. While cooling with ice, it is made alkaline with saturated potash solution, extracted with ethyl acetate, washed neutral, dried and evaporated to dryness in vacuo. The residue is triturated with a little petroleum ether, then recrystallized from 75% methanol. 0.65 g of H-Pro-Leu-Glu (OtBu) -Phe-OtBu with a melting point of 188-190 ° are obtained.

The starting material can be made as follows:

535 g (10mmol) N-2- (p-biphenylyl) -isopropyloxycarbonyl-proun-dicyclohexylammonium salt in 40 ml of dimethylformamide are mixed with 1.25 ml of privaloyl chloride at -15 ° -LeU-GIu (OtBu) -Phe-OtBu-acetate in 30 ml of dimethylformamide is added dropwise and the mixture is left to react for ^{2 hours at 0 c.} Then dilute with liquid ester and shake the solution at 0 ° twice with water. Ο, ί-M. Citric acid solution. 2-N soda solution and water. After drying over sodium sulfate, the ethyl acetate solution is evaporated to dryness, the residue is dissolved in ether and allowed to crystallize. This gives 6.75 g of N-2- (p-biphenylyl) -isopropyloxycarbonyl-Pro-Leu-Glu (OtBu) -Phe- OtBu, which, after recrystallization from 85% methanol, melts at 188 ° (decomposition).

Example 9

Application of the N-2- (p-biphenylyl) -isopropyl-

oxycarbonyl group in the

Solid support synthesis

Manufacture of carbobenzoxy-L-phenylalanyl-

L- (N ^f -tert. Butyloxycarbonyl) -lysyl-glycine-

hydrazide

2.15 g of BOC glycine resin (styrene-divinylbenzene copolymer containing 0.25 m Aeq BOC-glycine / g resin = 0.5 mmol) are treated with 10 ml of dioxane for 3 minutes stirred, then filtered. After adding 10 ml of 4N hydrochloric acid in dioxane, the mixture is 30 minutes at room temperature stirred uid washed three times each with 10 ml of dioxane and methylene chloride, each time for 3 minutes is stirred with the solvent. Now 10 minutes with 10 ml of a mixture of methylene chloride-triethylamine (9: 1) stirred and washed six times with 10 ml of methylene chloride. The H-glycine resin is stored under methylene chloride.

0.83 g of N * -2- (p-biphenylyl) -isopropyloxycarbonyl-N ^t -BOC-lysine-dicyclohexylammonium salt (1.25 mmol) are dissolved in methylene chloride, at 0 ° three times with 0.2 M citric acid solution and three times with Water shaken out. The methylene chloride solution is dried, filtered and concentrated to a few ml in vacuo. This solution is added to the above resin, stirred for 5 minutes, then 290 mg of dicyclohexylcarbodiimide, dissolved in a little methylene chloride, are added. After stirring for 3 hours, the mixture is filtered and washed three times each with 10 ml of methylene chloride, dimethylformamide, dimethylformamide-methanol (1: 1) and methylene chloride. The N * -2- (p-biphenylyl) -isopropyloxycarbonyl-N ^f -BOC-Lys-Gly resin is then suspended in 5 ml of methylene chloride and with 3.7 ml of a solution of 37.5 g of chloroacetic acid in 12.5 ml Water added. The _{mixture is stirred for a further 2} hours, then washed as above with methylene chloride, dioxane, methylene chloride, methylene chloride-triethylamine (9: 1) and methylene chloride. The H-Lys (BOC) -Gly resin obtained is stirred for 5 minutes after the addition of 0.37 g of carbobenzoxy-L-phenylalanine (Z-Phe-OH) in 8 ml of methylene chloride, then 290 mg of dicyclohexylcarbodiimide in a little methylene chloride are added and Stirred for 3 hours. The Z-Phe-Lys (BOC) -Gly resin is again filtered as above and washed with methylene chloride, dimethylformamide, dimethylformamide-methanol (1: 1), methanol and ethanol. The resin is then stirred with 10 ml of ethanol hydrazine hydrate (3: 1) for 15 hours, filtered off and washed several times with ethanol. The combined filtrates are evaporated to dryness in vacuo and the residue is dried over concentrated sulfuric acid in a high vacuum at 50 ° to remove the hydrazine hydrate Water. After inoculation, the mixture is allowed to cool slowly to room temperature. The crystallized product is filtered off and washed with ethanol-water (1: 3). 185 mg of Z-Phe-Lys (BOC) -Gly-NHNHivomF are obtained. 163-164 °.

Example 10

Production of L-propyl-L-tyrosyl- (N ^£ -tert.-butyloxycarbonyl) -L-lysyl-L-methionine-

hydrazide using the 2-p-biphenylylisopropyioxycarbonyl group

a) 6.7 g (10 mmol) of N * -2- (p-biphenylyl) -isopropyloxycarbonyl-N ^e -BOC-L-lysine-dicyclohexylammonium salt in 40 ml of dimethylformamide are stirred with 1.25 ml of pivaloyl chloride at -15 ° added and stirred for 5 minutes at -10 °. Then, while passing nitrogen over it, 2.0 g of L-methionine methyl ester hydrochloride and 1.4 ml of triethylamine are added and the mixture is stirred at 0 ° for 3 hours. It is diluted with ethyl acetate, shaken out three times at 0 ° with 0.1 M citric acid solution and at room temperature with 2 N potassium carbonate solution and water, dried and evaporated to dryness in vacuo. The crude product (6.5 g) is filtered through a column of 150 g of silica gel in chloroform. 4.7 g of N * -2- (p-biphenylylJ-isopropyloxycarbonyl-N ^ BOC-L-lysyl-L-methionine methyl ester are obtained in the form of a colorless resin, Rf = 0.55 in chloroform-acetone (8: 2).

b) 3.15 g (5 mmol) of this dipeptide ester are stirred with 50 ml of a mixture of glacial acetic acid-82.8% formic acid-water (7: 1: 2; VoI) for 1V for ₂ hours, then in a mixture of Pour 50 ml of ethyl acetate and 20 ml of saturated potassium carbonate solution at 0 °. The ethyl acetate solution is washed with water, dried and gently evaporated. The N ^f -BOC-L-lysyl-L-methionine methyl ester obtained is unstable and must be processed further immediately.

c) For this purpose, the residue is dissolved under nitrogen at 0 ° in 18 ml of acetonitrile with a Solution of 2.10 g (5 mmol) of N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-tyrosine (released from the cyclohexylammonium salt with citric acid) in 2 ml of dimethylformamide and 1.15 g of dicyclohexylcarbodiimide are added and the mixture is stirred at 0 ° for 20 hours. The unusual one Dicyclohexylurea is filtered off, the filtrate is evaporated, the residue is triturated with ether-petroleum ether, filtered off and reprecipitated from ethyl acetate-petroleum ether. 2.8 g of N-2- (p-biphenylyl) isopropyloxycarbonyl-L-tyrosyl-N'-BOC-L-lysyl-L-methionine methyl ester are obtained as a uniform powder according to thin-layer chromatography; Rf = 0.2 in chloroform-acetone (8: 2).

d) 238 g (3 mmol) of this tripeptide ester are mixed with 30 ml of a mixture of glacial acetic acid-82.8% formic acid-water (7: 1: 2; VoI) 1 hour at room temperature touched. The solution is poured into ice water. extracted twice with ether, the aqueous solution with saturated potassium carbonate solution and alkalized with Ethyl acetate extracted After evaporation of the ethyl acetate, U3 g of L-tyrosyl-ISKBOC-L-lysyl-L-methionine methyl ester remain in the form of a colorless foam. Rf = 03 in chloroform-methanol (85:15).

e) 1.1! g {2 mmol) of this tripeptide ester are dissolved with 0.71 g {2 mmol) N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-prohti (released from the dicyclohexylammonium salt) in 6 ml acetonitrile at 0 ° with 450 mg dicyclohexylcarbodiimide added and stirred for 18 hours at 0 ^c . The precipitated dicyclohexylurea is filtered off the filtrate is diluted with ethyl acetate at 0 ° three times with 0.1 M citric acid, extracted at room temperature with 2-Ti potassium carbonate solution and water, dried and evaporated to dryness in vacuo. 2- (p-Biphenyiyi) -isopropyloxycarbonyl L-prolyl-L-tyrosyl-N ^ BOC-L-lysyl-L-methionine methyl ester is obtained in quantitative yield (1.8 g).

f) He is with 22 ml of a mixture of glacial acetic acid 82.8% formic acid-water (7: 1: 2) for 1 hour touched. The solution is mixed with ice water, extracted twice with ether, and the aqueous solution is made Solution with saturated potassium carbonate solution is alkaline and extracted with ethyl acetate. After the dryer the ethyl acetate is completely evaporated in vacuo

, ο What remains is 1.02 g of L-Prolyl-L-tyrosyl-N'-BOC-L-lysyl-L-methionine methyl ester, Rf = 0.25 in chloroform-methanol (85:15). The product can be crystallized from acetonitrile; 177-180 ° F.

g) 326 mg (0.5 mmol) of the tetrapeptide ester are dissolved in 1 ml of hot methanol, while passing over 0.25 ml of hydrazine hydrate are added to nitrogen at room temperature and stand closed for 18 hours calmly. The product that has crystallized out is filtered off! and washed with water. 225 mg are obtained L-prolyl-L-tyrosyl-Nf-BOC-L-lysyl-L-methionine hydrazide from the F. 206 -207 °.

Example 11

2s production of L-prolyl-L-tyrosyl-

L- (N ^E -tert.-butyloxycarbonyl) -lysyl-

L-methionine hydrazide after solid support synthesis using the 2- (p-biphenylyl) isopropyloxycarbonyl group

a) 4.9 g of BOC methionine resin (styrene-divinylbenzene copolymer containing 0.18 m aeq. BOC-methionine / g resin = 0.88 mmol) are in a 50 ml reaction Merrifield vessel shaken under nitrogen successively with the following reagents, each again to be filtered off:

1. with 25 ml of dioxane for 4 minutes:

2. with 20 ml of 4N HCl in dioxane for 60 minutes: 3. 3 times with 20 ml of dioxane each time for 3 minutes;

4. 3 times with 20 ml of ethanol each time for 3 minutes;

5. 3 times with 20 ml of chloroform each time for 3 minutes;

6. with 20 ml of chloroform-triethylamine (9: 1) for 10 minutes;

7. 3 times with 20 ml of chloroform each time for 3 minutes:

8. 4 times with 20 ml of methylene chloride each time for 3 minutes.

The methione resin obtained is methylene chloride stored moist (contains a total of 17 ml methylene chloride) From 1.87 g of N * -2- (p-biphenylyl) -isopropyloxycarbonyi NMert.-butyloxycarbonyl-L-lysine dicyclohexyiammonium salt is there as described in example 9! protected L-lysine released. The methy Lene chloride solution is added to the above resin, shaken for K minutes then a solution of 730 mJ Add dicyclohexylcarbodiimide in 3 ml of methylene chloride and shake the whole thing for 4 hours. There; Resin is then washed with shaking as follows:

3ma! with 20 ml of methylene chloride each (3 minutes each); 3 times with 20 ml of methanol each time (3 minutes each time) and 3 times with 20 ml of methylene chloride each time (3 minutes each time).

The obtained N * -2- (p-biphenylyl) -isopropyloxycar

6s bonyl-N ^ BOC-L-lysyl-L-methionine resin (contains 17 m Methylene chloride) is used to split off the N * -2- (p-Di phenyl) isopropyloxycarbonyl group with 12.6 ml of a 75% aqueous chloroacetic acid solution added

Shaken 1V for ₂ hours. The resin is filtered off and washed with shaking as follows:

3 times with 20 ml of methylene chloride each time (3 minutes each time);

4 times with 20 ml of ethanol each time (3 minutes each time); 1 time with 25 ml of chloroform (3 minutes); once with 20 ml of chloroform triethylamine (9: 1) (10 Minutes);

3 times with 20 ml of chloroform each time (3 minutes each time);

3 times with 20 ml of methanol each time (3 minutes each time) and 3 times with 20 ml of methylene chloride each time (3 minutes each time).

The N'-BOC-L-lysyl-L-methionine resin obtained is then reacted with N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-tyrosine in a manner analogous to that above. For this purpose, 1.6 g of the cyclohexylammonium salt of this compound are reacted stirred at 0 ° with 25 ml of ethyl acetate and 20 ml of 1-M citric acid solution until everything is dissolved. The aqueous layer is separated off, the ethyl acetate solution is washed, dried and evaporated to dryness in vacuo. The crystalline residue is dissolved in 1 ml of dimethylformamide, with 10 ml! Diluted methylene chloride and added the solution to the above resin. At the same time, 710 mg of hydroxysuccinimide are added. After shaking for 10 minutes, a solution of 700 mg of dicyclohexylcarbodiimide in 5 ml of methylene chloride is added and the mixture is shaken for 4 hours. The resin is then washed as described above with methylene chloride, methanol and methylene chloride. To split off the N-2- (p-biphenylyl) -isopropyloxycarbonyl group with chloroacetic acid one proceeds exactly according to the above procedure. The L-tyrosyl-N ^£ -BOC-L-lysyl-L-methionine resin is obtained in this way, which with N-2- (p-diphenyl) -isopropyloxycarbonyl-L-proline in methylene chloride (obtained from a solution of 1.34 g of the dicyclohexylammonium salt is condensed in methylene chloride by releasing it with citric acid). The methylene chloride solution obtained is shaken with the resin for 10 minutes, then a solution of 580 mg of dicyclohexylcarbodiimide in 5 ml of methylene chloride is added and shaken for 18 hours. The resin is filtered off, washed immediately as described above and the N-2- (p-biphenylyl) isopropyloxycarbonyl group is split off with chloroacetic acid. After the usual washing processes, the L-prolyl-L-tyrosyl-N ⁽ - BOC-L-lysyl-L-methionine resin obtained is shaken with 20 ml of ethanol, filtered and, under a gentle stream of nitrogen, with 7 ml of ethanol and 3 ml Hydrazine hydrate is stirred for 17 hours. The resin is filtered off and washed ten times with 10 ml of 95% ethanol each time. The combined filtrates are evaporated in vacuo at 50 ° and the residue is dried under high vacuum over sulfuric acid. The crude product is dissolved in 25 TiI 0.1 Acetic acid and 80 ml of ethyl acetate and shake out the aqueous solution twice more with 50 ml of ethyl acetate each time. The three ethyl acetate solutions are extracted twice more with 10 ml of 0.1 N-acetic acid each time. All three aqueous extracts are combined and lyophilized. Further purification is carried out by chromatography on 7 g of CM-Sephadex with the aid of a gradient consisting of 300 ml each of 0.01 m and 0.05 m ammonium acetate with a pH of 6.5. The pure fractions are combined and lyophilized 3 20 mg of the acetate of L-prolyl-L-tyrosyl-N ^e -BOC-L-lysyl-L-methionine hydrazide. The product is completely identical to the product described in Example 10. Rf = 0.35 in the thin-layer chromatogram in the s-butanol-glacial acetic acid-water system (67:10:23). After liberation from the acetate with potassium carbonate solution, the product crystallizes from aqueous methanol, mp 206 ° -207 ° (decomp.).

Example 12

Preparation of N-2- (p-biphenylyl) -isopropyI-oxycarbonyl-L-leucyl-L-valyl-S-trityl-L-cysteinyl-glycyl-L-glutamic acid di-tert-butyl ester

The S-trityl-L-cysteinyl-glycyl-L-glutamic acid di-tert-butyl ester required as starting material can be prepared as follows: From carbobenzoxyglycine and L-glutamic acid di-tert-butyl ester becomes with the mixed anhydride method carbobenzoxy-glycyl-L-glutamic acid-di-tert-butyl ester preserved, F. 74 - 76 °. The glycyl-L-glutamic acid-di-tert-butyl ester obtained therefrom by hydrogenation is with N.S-Di-trityl-L-cysteine and dicyclohexylcarbodiimide reacted and supplies N.S-Di-trityl-L-cysteinyl-glycyl-L-glutamic acid di-ter ».- butyl ester, 98-110 °. By splitting off the 1, -trityl group with 80% acetic acid S-trityl-L-cysteinyl-glycyl-L-glutamic acid di-tert-butyl ester is obtained.

N-2- (p-Biphenylyl) -isopropyloxycarbonyI-L-valine (from 1.91 g [4.2 mmol] of the cyclohexylammonium salt released with citric acid) is dissolved in 20 ml of ethyl acetate, 0.59 ml (4.2 mmol) of triethylamine and, after cooling to -10 °, 0.56 ml (4.2 mmol) of isobutyl chlorocarbonate to. After stirring for 10 minutes at -10 °, a solution of 2.78 g (4.2 mmol) is added dropwise. of the above tripeptide diester in 25 ml of ethyl acetate to and stirs for a further 15 minutes at -10 ° and 1 hour at room temperature. After diluting with ethyl acetate it is shaken out at 0 ° with 0.5 m citric acid, 1 n sodium hydrogen carbonate and water, and dried and steam to dryness. The residue, crystallized from acetone-ether, gives 2.91 g of N-2- (p-biphenylylJ-isopropyloxycarbonyl-L-valyl-S-trityl-L-cyste- Inylglycyl-L-glutamic acid di-tert-butyl ester from F. 184-186 °. Rf = 0.6 in chloroform-methanol (95: 5).

1 g (1 mmol) of this tetrapeptide ester are mixed with 10 ml of a mixture of glacial acetic acid-82.8% ige ant

4S acid-water (7: 1: 2, vol) 1 hour at room temperature touched. After adding 10 ml of water and 40 ml of chloroform, concentrated ammonia is added at 0 ° alkalized, the chloroform solution separated off, washed, dried and in a vacuum to dryness evaporated. The residue is triturated with petroleum ether, 0.76 g of L-valyl-S-trityl-L-cysteinyl-glycyl-L-glutamic acid di-tert-butyl ester is obtained as an oil which is uniform by thin-layer chromatography. Rf = 0.25 in chloroform-methanol (95: 5). To 370 mg (1 mmol) of N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-leucine and 768 mg of the above tetrapeptide ester in 7 ml of tetrahydrofuran are 238 mg of dicyclohexylcarbodiimide at 0 ° added and stirred at 0 ° for 4 hours. After filtering off the dicyclohexylurea is with Diluted ethyl acetate, washed at 0 ° with 0.5 m citric acid, 1-n sodium hydrogen carbonate and water, dried and evaporated. By eluting with ethyl acetate in the chromatography on silica gel 775 mg N-2- (p-biphenylyl) -isopropyloxycarbonyl-L-leucyl-L-valyl-S-trityl-L-cysteinyl-glycyl-L-glutamine- acid di-tert-butyl ester obtained as a uniform product. Rf = 0.55 in chloroform-methanol (9: 1); Rf = 0.63 in toluene-acetone (1: 1).

Example 13

Introduction of the 1,1-biphenylyl-ethoxycarbonyl group

8.2 g of biphenylyl-methyl-carbinol, 5.35 g of isocyanate acetic acid ethyl ester and 4 ml of pyridine are heated to 50 ° for 48 hours. The solution is made with 100 ml of ether diluted, extracted at 0 ° with 0.1 m citric acid solution and water, dried over sodium sulfate and completely evaporated in vacuo. 10.6 g of a viscous oil are obtained, consisting of 1,1-diphenyl-ethoxycarbonyl-glycine-ethyl ester; Rf = 0.7 in the thin-layer chromatogram in chloroform-methanol (95: 5).

Example 14

Cleavage of the l, l-bipheny) yJ-ethoxycarbonyl group

207.8 mg of U-biphenylyl-ethoxycarbonyl-glycine-ethyl ester are dissolved in 3.15 ml of 80% acetic acid at 25 °. After various times, samples of 0.20 ml removed, added to 4 ml of dimethylformamide and the liberated glycine ethyl ester with 0.1 n-perchloric acid titrated. The half-life for splitting off the protective group is approx. 30 minutes. After 5 Hours, the split is quantitative.

Example 15

Introduction of the 1,1-biphenylyl-propyloxycarbony group

3.2 ε biphenylyl-ethyl-carbinol, 1.9 g of ethyl isocyanate acetate and 1.6 ml of pyridine are heated to 50 ° for 72 hours. The solution is mixed with 50 ml of ether diluted, at 0 "several times with 0.1 m citric acid solution and water, dried over sodium sulfate and completely evaporated in vacuo. After separating 2.3 g of biphenylyl-ethylcarbinol 1,1-BiphenylyI-propyIoxycarbonyl-glycine-ethyl ester is obtained by means of petroleum ether obtained as an oil; Rf = 0.2 in the thin-layer chromatogram in chloroform.

Example 16

Cleavage of the 1,1-biphenylyl-propyloxycarbonyl group

409 mg of 1,1-biphenylyl-propyloxycarbonyl-glycine ethyl ester are dissolved in 80% acetic acid at 22 °. After various times, samples of 0.5 ml taken, added to 4 ml of dimethylformamide and \ s the glycine ethyl ester released with 0.1 n-perchloric acid titrated. The half-life for splitting off the protective group is approx. 50 minutes. After 8 hours the connection is split quantitatively.

Claims (1)

Patent claims: 1. N-acyl-protected amino acids and peptides and their derivatives of the general formula Ac-NH (D wherein -NH-A is the residue of an amino acid or of a peptide, or a derivative thereof, and Ac denotes the group Invention of N-acyl-protected amino acids and peptides, as well as their derivatives, of the general formula