JPS5929051B2 - Method for producing 2-alkyl-2-cyclopentenone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2-alkyl-2-cyclopentenone useful as a jasmine fragrance and an intermediate thereof.

2-Alkyl-2-cyclopentenone has been used as a diasmine fragrance and as a synthetic intermediate, and is an important compound in the fragrance industry, and many studies have been conducted on its synthesis from various raw materials.

For example, as a conventionally known synthesis method, there is a method that appears in the following literature. 8 P.A.Plattner,,A.
, S., Pfau, Helv.

Chim, Acta, 1474 (1937) (
B) I, J, Rinkes, Rec, Trav, Chi
m,, ■176 (1938) (〇M, F, Ansell
, ,J.W.,Ducker, ,J.,Chim.

Soc,, 1959329 old M, F, Ansell,
, T, M, Kafka) Tetrahedron Danj6
025 (1969) However, the conventionally known synthesis method of 2-alkyl-2-cyclopentenone has a poor yield.
2. It cannot be obtained at a low price. 3. It has the disadvantages that it cannot be obtained as a pure product.

For example, in the literature of the time, 2-hexylidenecyclopentanone is isomerized with polyphosphoric acid, and 2-n-hexylidene-2-
Although cyclopentenone (Isodia Sumon) has been obtained, the yield is only about 10%, which is extremely low. The inventors have 2
- As a result of intensive research on the production method of alkyl-2-cyclopentenone, the present invention was achieved.

The feature of the present invention is that 2-alkylidenecyclopentenone is isomerized to synthesize 2-alkyl-2-cyclopentenone in good yield.

Therefore, the present invention can be said to be an improved method of Document D, but
The method in Document D involves isomerization using polyphosphoric acid, and the yield is extremely low.

As a result of research on this isomerization reaction, the present inventors found that instead of polyphosphoric acid, a platinum group element compound that can move double bonds and a specific transition metal carbonyl compound, which is a low valence compound, were used as a catalyst. It has been found that the above-mentioned drawbacks can be improved and 2-alkyl-2-cyclopentynones can be obtained in high yield. Here, the raw material 2-alkylidenecyclopentanone (1X) is converted into a realdol adduct (5) from cyclopentanone (3) and the corresponding aldehyde (4) using a base catalyst as shown in the reaction formula below. It is then easily obtained by dehydration or by reacting cyclopentanone (3) with a secondary amine (6) to give enamine (7), and reacting it with the corresponding aldehyde, and is an extremely inexpensive raw material. be.

That is, the present invention provides 2-
A general formula characterized in that alkylidenecyclopentanone is brought into contact with a salt or complex of a platinum group element, or a carbonyl complex of iron, manganese, cobalt, nickel, titanium, chromium or molybdenum (wherein R has 2 to 8 carbon atoms) 2-
A method for producing alkyl-2-cyclopentynones is provided.

Specific examples of the platinum group element compounds and specific transition metal carbonyls used as catalysts in the present invention include the following.

As the platinum group element compound catalyst, salts or complexes of platinum group elements are used, and salts and complexes of platinum, iridium, palladium, rhodium, and ruthenium are particularly preferably used.

For example, PdCl2, PdBr2, Pdl2, PhCl3
, Ptcl2, IrCl3, RuCl3, H2PtCl
6, H2lrCl6, Na2Pd2Cl6, Li2Pd
Salts of platinum group elements represented by Cl4, [(C2H4)
2RhC1]2[(C2H4)2PtC12J2,C8
Olefin complexes of salts of platinum group elements represented by Hl2PdCl2 (C2H4 represents ethylene and C8Hl2 represents cyclooctadiene; the same applies hereinafter), PdX2 (PhCN)
Nitrile complex represented by (X: Cl.Br.I), P
dCl2(PPh3)2, PdBr2(PPh3)3,
RllCl(PPh3)3, RhCl3(PPh3)3
, PdI2(Me2PhP)2, (Et3P)2PtH
C1, phosphine complex of platinum group element salt represented by RHCl2(PPh3)3, HRh(PPh3)3, Ir
Platinum group element hydrides represented by H3(PPh3)3, IrHCl2(PPh3)3, PdCl2(CO)2,
PtCl2(CO)2, [PtBr2(CO)2]2,
RhCl(CO)2, RhBr(CO)2, IrCl(
CO)3, IrBr2(CO)2, IrHCO(PPh
3) A carbonyl complex of a salt of a platinum group element represented by 3, PhH(CO)(PPh3)3 is effective as a catalyst.

Furthermore, by adding hydrogen halides, organic acids, sulfuric acid, and alcohols to this catalyst system, it may be possible to further enhance its effectiveness as a catalyst. Furthermore, in cases where the metal is precipitated, the addition of Sncl2 is particularly effective. Next, the carbonyls of transition metals include iron,
Carbonyl compounds whose central metals are manganese, cobalt, nickel, titanium, chromium, and molybdenum are used. For example, Fe(CO)5, Fe2(CO)9, Fe3
(CO)12, Ni(CO)4, Cr(CO)6, MO
Transition metal carbonyl of (CO)6, CO2(CO)8, Mn2(CO)10, Cl2Fe(CO)-Br2Fe
(CO)4, BrMn(CO)5, COI(CO)2(
Transition metal carbonyl halides represented by PPh3)2, HCO(CO)4, H2Fe(CO)4, Na
HFe(CO)4, C5H5Cr(CO)3H. HMr.
Transition metal hydrides represented by 1(CO)5, HCO(CO)3PPh3 (C5H5 represents cyclopentadienyl; the same applies hereinafter), Fe(CO)4PPh3, CO2(
CO)6(PPh3)2, Mn2(CO)8(PPh3
) transition metal carbonylphosphine complex represented by 2,
(C5H5)2Ti(CO)2, [C5H5Cr(CO
)3]2, [C5H5Fe(CO)2]2, [C5H5
NiCO]2, C5H5CO(CO)2, C5H5Mn
Cyclopentadienyl transition metal carbonyl represented by (CO)3, CH3Mn(CO)5, CH3CO(CO
) a transition metal carbonyl alkyl complex represented by 4,
The transition metal carbonyl olefin and allene complexes shown below are effective as catalysts.

Next, the implementation of the present invention will be explained in more detail.

By contacting 2-alkylidenecyclopentanone (1) with a platinum group element compound catalyst or a transition metal carbonyl catalyst, usually in a homogeneous system, the corresponding 2-alkyl-2-cyclopentynone can be obtained with a yield of usually 50 to 95%. (2) can be obtained.

Although there is no particular restriction on the amount of the catalyst based on the raw material (1), it is preferably used in an amount of 1 to 50 mol%. The reaction temperature is O'C
The temperature range is 200°C. Especially 70~150℃
A range of is preferred. A solvent may or may not be used.

When using methanol, ethanol, propanol,
Alcohols such as butanol and pentyl alcohol, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane, octane and decalin, butyl ether, ethyl ether,
Ethers such as tetrahydrofuran diethylene glycol and diethyl ether, and ketones such as acetone and methyl ethyl ketone are usually used. In particular, when platinum group element compounds are used as catalysts, alcohol,
Since the catalytic effect is often enhanced when the reaction is carried out in an organic acid or phenol, these solvents are particularly preferred. When a transition metal carbonyl is used as a catalyst, hydrocarbon and ether solvents are particularly preferred from the viewpoint of stability of the complex.
Next, specific examples of the present invention will be shown.

Example 1 2-n-pentylidenecyclopentanone (7.67,0
．． 05m01) in n-butanol (50m1) and palladium chloride (0.447, 0.0025m0) was dissolved in n-butanol (50m1).
1) was added, and the mixture was heated and stirred at 100°C for 2 hours.

The solvent is distilled off under reduced pressure and the residue is rectified. B. p~81
C/2 mmHg yield was 5.97, gas chromatography analysis revealed that it was 2-n-pentyl-2-cyclobenzene, and no 2-n-pentylidenecyclopentanone, a raw material, was contained. Yield 76%. The yields of the corresponding 2-alkyl-2-cyclopentynones in the same manner were 75%, 77%, 74%, 80%, and 7, respectively.
It was 9%.

Example 2 {2-n-hexylidenecyclopentanone (16.4
y,. 0.1m01) to n-butanol (100m1)
RhCl33H2O (1.32V,
0.005m01) was added, and the mixture was heated and stirred at 100°C for 2 hours.

After distilling off the solvent under reduced pressure, the residue was purified by rectification of 2-n-hexyl-2-cyclopentynon (isojasmone) (B.pl
l7℃/2m77IHg yield 13.8ynW=1.46
34 (yield 84%) was obtained. Example 3 PdBr2, PdI2, Na
2Pd2Cl6, Li2PdCl4, PtCl2, H2
PtCl6, RUCl3・H2O, IrCl3・4H
Table 1 shows the results using No. 20 as a catalyst.

Example 4 2-isobutylidenecyclopentanone (13.8V, .
0.1m01) to [C8H,2RhCU2(0.29
V) 0.001m01) was added, heated and stirred at 150'C for 30 minutes, and then the product was distilled off under reduced pressure.

2-isobutyl-2-cyclopentynone (B.p6
5℃/2mWLHg) Yield 11.6V) Yield 84.0
%).

As a result of gas chromatography analysis, the rearrangement was complete and no raw material remained. Example 5 2-n-Butylidenecyclopentanone (13.87, 0.1 m01) was dissolved in ethanol (100 m1), and ClRh (
Add PPh3)3 (1.857, 0.002!MOl) and heat and stir at 85°C for 4 hours.

After distilling off the ethanol, the residue was distilled to give 2-n-butyl-
2-cyclopentynone (B. plO2°c/8 or 5WZ
UHg, yield 12.6V, yield 91.3%). Gas chromatography analysis revealed that the dislocation was complete;
There are no raw materials left. Example 6 Table 2 shows the results of using platinum group element compounds such as phosphine complexes, olefin complexes, hydrides, and carbonyl complexes as catalysts in the same manner as in Examples 4 and 5.

Example 7 2-n-pentylidenecyclopentanone (15.27,
Fe3(CO),2(0.47,0.1m01)
0008m01) was added, heated at 130°C for 6 hours, stirred, and then distilled under reduced pressure to obtain 2-n-pentyl-121cyclopentenone (9.3V, yield 61.2%).

There are no raw materials left. Example 8 2-n-pentylidenecyclopentanone (15.27,
0.1m01) was dissolved in n-hexane (50ml),
To this, HMn(CO)5 (1.96y10.01m0
Add 1) and stir at room temperature for 6 hours.

After distilling off the solvent, it is rectified under reduced pressure to give 2-n-pentyl-2
-Cyclopentinone (11.9y, 78.3%) was obtained. Example 9 2-n-hexylidenecyclopentanone (
517, 0.333m01) and Fe(CO)5(2.0
7), heated and stirred at 115°C for 7 hours, and then rectified under reduced pressure to obtain 2-n-hexyl-2-cyclopentynon (
40.3y, yield 79.0%) was obtained.

Claims (1)

[Claims] 1 2- represented by the general formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (where R is an alkyl group having 2 to 8 carbon atoms)
General formulas characterized by contacting alkylidenecyclopentanone with salts or complexes of platinum group elements or carbonyl complexes of iron, manganese, cobalt, nickel, titanium, chromium or molybdenum ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R is an alkyl group having 2 to 8 carbon atoms)
Method for producing alkyl-2-cyclopentenone.