JP3590880B2 - New iridium complex - Google Patents

Description

ＴＨＦ （１０ ｍｌ） 中で金属ナトリウム （１２ ｍｇ， ０．５２ ｍｍｏｌ） とフルオレノン （９４ ｍｇ， ０．５２ ｍｍｏｌ） から褐色のナトリウム−フルオレノンケチルを合成し、これを暗青色の［（Ｃｐ^＊ ）ＩｒＣｌＨ］_２ （Ｇｉｌｌ， Ｄ．Ｓ． ａｎｄ Ｍａｉｔｌｉｓ， Ｐ．Ｍ． Ｊ． Ｏｒｇａｎｏｍｅｔ． Ｃｈｅｍ．， ８７， ３５９， １９７５） （１７１ ｍｇ， ０．２６ ｍｍｏｌ）の ＴＨＦ溶液 （１０ ｍｌ）に加え、室温で３時間攪拌して褐色懸濁液を得た。この懸濁液を濾過し、濾液を乾固した後に残渣をベンゼンから再結晶して、［（Ｃｐ^＊ ）ＩｒＨ］_２ ・２ フルオレノンを黒褐色結晶 （２５４ ｍｇ， ０．２５ ｍｍｏｌ）として得た（収率 ９７％）。
【００１１】
例２：本発明のイリジウム錯体の製造（方法２）
【化２】

金属カリウム （３９ ｍｇ， １．００ ｍｍｏｌ） に［（Ｃｐ^＊ ）ＩｒＣｌＨ］_２ （３６４ ｍｇ， ０．５０ ｍｍｏｌ）のＴＨＦ 溶液 （１０ ｍｌ）を加え、室温で６時間攪拌して褐色懸濁液を得た。この懸濁液を濾過し、濾液を乾固した後、残渣をヘキサンで洗浄して［（Ｃｐ^＊ ）ＩｒＨ］_２を黒褐色固体 （３１２ ｍｇ， ０．４７ ｍｍｏｌ）として得た（収率 ９４％） 。
【００１２】
^１Ｈ ＮＭＲ （Ｃ_６Ｄ_６， ２２ ℃）：δ １．８１ （ｓ， ３０Ｈ， Ｃｐ^＊ ）， −１３．４２ （ｓ， ２Ｈ， Ｉｒ−Ｈ）
^１３Ｃ ＮＭＲ （Ｃ_６Ｄ_６， ２２ ℃）：δ ８５．５ （Ｃｐ^＊ ）， １１．７ （Ｃｐ^＊ ）
［（Ｃｐ^＊ ）ＩｒＨ］_２ ・２ フルオレノンの結晶Ｘ線解析 （図１） ：Ｃ_４６Ｈ_４８Ｏ_２Ｉｒ_２，
結晶データ： Ｆ_ｗ ＝１０１７．３３， トリクリニック， 空間群：Ｐ−１
ａ＝８．７２２（４）Å， ｂ＝１０．５７１（２） Å， ｃ＝１１．７８８（２） Å
α＝ １０４．０１°， β＝ ９６．８９（２）°， γ＝ ６６．６７（２）°，
ｖ＝９６８．０（５）Å^３， Ｚ＝１， Ｄ_ｃ ＝１．７５ ｇ ｃｍ^−３， Ｒ＝０．０７５７， Ｒ_ｗ ＝０．０８９６
【００１３】
例３：本発明の錯体を用いたベンゾピナコールの炭素−炭素結合切断反応
【化３】

例２で得た本発明の錯体 （７ ｍｇ， ０．０１ ｍｍｏｌ）とベンゾピナコール （３６６ ｍｇ， １．００ ｍｍｏｌ）をトルエン （１０ ｍｌ）中、６５℃で １日反応させた。^１Ｈ ＮＭＲより、原料のベンゾピナコールが消失し、ベンズヒドロールとベンゾフェノンが定量的に生成していることが確認された。反応混合物に水を加え、生成物をエーテルで抽出してＴＬＣ により分離した。ベンズヒドロール （１７０ ｍｇ， ０．９２ ｍｍｏｌ）の収率は ９２％、ベンゾフェノン （１６４ ｍｇ， ０．９０ ｍｍｏｌ）の収率は ９０％であった。本発明の錯体の原料である［（Ｃｐ^＊ ）ＩｒＣｌＨ］_２を用いた場合には、ピナコールの中心炭素−炭素結合は切断されなかった。
【００１４】
例４：本発明の錯体を用いた１−ヘキセンの異性化反応
例２で得た本発明の錯体 （１０ ｍｇ， １．５×１０^−２ ｍｍｏｌ）と１−ヘキセン （０．１９ ｍｌ， １．５ ｍｍｏｌ）を重ベンゼン （０．５ ｍｌ） 中、室温で反応させた。^１Ｈ ＮＭＲより２−ヘキセンへの異性化が起こっていることが確認された。反応はゆっくり進行し、３週間後にほぼすべての１−ヘキセンが２−ヘキセンへ異性化した。
【化４】

【００１５】
【発明の効果】
本発明の新規イリジウム錯体は、例えばベンゾピナコール類の炭素−炭素結合切断反応やアルケン類の異性化用の触媒として有用である。
【図面の簡単な説明】
【図１】本発明のイリジウム錯体［（Ｃｐ^＊ ）ＩｒＨ］_２の構造を示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel iridium complex and its use.
[0002]
[Prior art]
As a pentamethylcyclopentadienyliridium complex having iridium as a central metal, for example, dihydridobis [chloro (pentamethylcyclopentadienyl) iridium and the like have been reported (Gill, DS and Maitlis, PM). ., Journal of Organometallic Chemistry, 87 , pp.359-364, 1975). this complex is known to be useful in the hydrogenation of olefins. Furthermore, alkali metal fluorenyl Straight chill and Cp ^* IrCl _{2] 2} It has been reported that the decarbonylation of fluorenone occurs in the reaction (Fujita et al., Spring Meeting of the Chemical Society of Japan 1997, Abstract No. 3E336, Tokyo).
[0003]
Problems to be Solved by the Invention and Means for Solving the Problems
An object of the present invention is to provide a novel iridium complex, and more specifically, to provide a novel binuclear iridium hydride complex. Another object of the present invention is to clarify the usefulness of the iridium complex and to provide a novel organic synthesis reaction. The present inventors have made intensive efforts to solve the above problems, and for the first time succeeded in producing a dihydride complex having an iridium-iridium triple bond, and this iridium complex efficiently reduces the carbon-carbon bond of benzopinacols. Cleavage to give the corresponding secondary alcohol compound and ketone compound. The present invention has been completed based on these findings.
[0004]
That is, the present invention provides an iridium complex represented by the formula: [CpIrH] ₂ (wherein Cp represents a cyclopentadienyl-based ligand, preferably a pentamethylcyclopentadienyl ligand) It is. In another aspect, the present invention provides a compound represented by the following formula (I): C (R ¹ ) (R ² ) (OH) -C (R ³ ) (R ⁴ ) (OH) wherein R ¹ , R ² , R ³ and R ⁴ each independently represent a substituted or unsubstituted aryl group, but the aryl groups represented by R ¹ and R ² may be bonded to each other, and / or R ³ and R 4 ^The aryl group represented by formula (4) may be bonded to each other) in the presence of a catalytic amount of the above iridium complex to give the following formula (II): CH (R ¹ ) (R ² ) (OH) (wherein R ¹ and R ² are as defined above) and formula (III): R ³ —CO—R ⁴ (wherein R ³ and R ⁴ are as defined above). A method of manufacturing is provided. From still another viewpoint, the iridium complex which is a catalyst for cleaving a pinacol carbon-carbon bond of an arylpinacol represented by the above formula (I); and the iridium complex which is a catalyst for isomerization of an alkene is provided. Is done.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
In the iridium complex of the present invention represented by the above formula, Cp represents a cyclopentadienyl-based ligand. As the cyclopentadienyl-based ligand, in addition to the cyclopentadienyl ligand, 1 to 5 identical or different _C1-4 alkyl groups, preferably the same 5 _C1-4 alkyl groups, And a cyclopentadienyl ligand, particularly preferably a pentamethylcyclopentadienyl ligand (which may be represented by Cp ^* in this specification) and the like.
[0006]
Among the above complexes of the present invention, a complex having a pentamethylcyclopentadienyl ligand as a ligand is a known iridium complex [Cp ^* IrClH] ₂ (Gill, DS and Maitlis, PM, J. Organomet. Chem., 87, 359, 1975) with sodium-fluorenone ketyl obtained by reacting metallic sodium with fluorenone. According to this method, a crystal may be obtained in which one or more moles of fluorenone and the like used in the reaction with sodium are incorporated. The complex of the present invention can also be produced by reacting the iridium complex with potassium metal. The complex of the present invention having another cyclopentadienyl-based ligand can also be produced in the same manner by producing a complex having the corresponding ligand according to the above-mentioned Gill et al. . Incidentally, since specific examples of these production methods are described in the examples, those skilled in the art can appropriately select starting materials, reaction conditions, and the like to convert the iridium complex of the present invention included in the above general formula. It can be easily manufactured.
[0007]
The iridium complex of the present invention represented by the above formula can be used as a catalyst for a pinacol carbon-carbon cleavage reaction of an arylpinacol or an olefin isomerization reaction. The carbon-carbon cleavage reaction of aryl pinacols provided by the present invention is represented by the following formula (I): C (R ¹ ) (R ² ) (OH) —C (R ³ ) (R ⁴ ) (OH) (OH) In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a substituted or unsubstituted aryl group, but the aryl groups represented by R ¹ and R ² may be bonded to each other; And / or the aryl groups represented by R ³ and R ⁴ may be bonded to each other) in the presence of a catalytic amount of the above iridium complex to give the following formula (II): CH (R ¹ ) (R ² ) (OH) (wherein R ¹ and R ² are as defined above) and formula (III): R ³ —CO—R ⁴ (wherein R ³ and R ⁴ are (Same as the above).
[0008]
In the compounds represented by the above formulas (I) to (III), as the aryl group, for example, a phenyl group, a naphthyl group or the like can be used, but a phenyl group is preferable. When the aryl group has one or more substituents, the type of the substituent is not particularly limited as long as it is substantially inert in the above reaction. For example, a C _1-4 alkyl group, a C _{1- A 4} alkoxy group, a halogen atom and the like can be used. When it has two or more substituents, they may be the same or different. The ring-constituting carbon atoms of the aryl group represented by R ¹ and R ² may be bonded to each other to form a 5- to 7-membered ring, preferably a 5-membered ring, together with the carbon atom to which R ¹ and R ² are bonded. . An example of such a case is when the compound represented by the formula (II) is fluorenol. The aryl groups represented by R ³ and R ⁴ may be bonded to each other to form a 5- to 7-membered ring, preferably a 5-membered ring, with the carbon atom to which R ³ and R ⁴ are bonded. An example of such a case is when the compound represented by the formula (III) is fluorenone.
[0009]
The above reaction is carried out, for example, in an inert solvent such as toluene, in an amount of about 0.0001 to 0.1 mol, preferably about 0.005 to 0.05 mol, per 1 mol of the compound of the above formula (I). Of the above iridium complex. The concentration of the compound of the formula (I) in the solution is not particularly limited, but the reaction can be carried out, for example, at a concentration of about 1 to 10% (V / V), preferably about 5% (V / V). The reaction temperature is not particularly limited, and the reaction can be carried out at a temperature from 0 ° C. to the boiling point of the solvent, preferably at a temperature from room temperature to about 100 ° C.
[0010]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples.
Example 1: Production of iridium complex of the present invention (method 1)
Embedded image

A brown sodium-fluorenone ketyl was synthesized from metallic sodium (12 mg, 0.52 mmol) and fluorenone (94 mg, 0.52 mmol) in THF (10 ml) and this was dark blue [(Cp ^* )]. IrClH] ₂ (Gill, DS and Maitlis, PMJ Organomet. Chem., 87, 359, 1975) (171 mg, 0.26 mmol) in THF solution (10 ml) and room temperature. For 3 hours to obtain a brown suspension. The suspension was filtered, the filtrate and the residue was recrystallized after dryness from ^benzene, was obtained as _{[(Cp *) IrH] 2} · 2 fluorenone dark brown crystals (254 mg, 0.25 mmol) ( Yield 97%).
[0011]
Example 2: Preparation of iridium complex of the present invention (method 2)
Embedded image

To a potassium metal (39 mg, 1.00 mmol), a THF solution (10 ml) of [(Cp ^* ) IrClH] ₂ (364 mg, 0.50 mmol) was added, and the mixture was stirred at room temperature for 6 hours to give a brown suspension. Got. The suspension was filtered and the filtrate was evaporated to dryness. The residue was washed with hexane to obtain [(Cp ^* ) IrH] ₂ as a black-brown solid (312 mg, 0.47 mmol) (yield 94%). ).
[0012]
¹ H NMR (C ₆ D ₆ , 22 ° C.): δ 1.81 (s, 30 H, Cp ^* ), −13.42 (s, 2 H, Ir-H).
¹³ C NMR (C ₆ D ₆ , 22 ° C.): δ 85.5 (Cp ^* ), 11.7 (Cp ^* )
_{^{[(Cp *) IrH] 2}} · 2 crystal X-ray analysis of fluorenone (Figure _{1): C 46 H 48 O} 2 Ir 2,
Crystal data: F _w = 1017.33, triclinic, space group: P-1
a = 8.722 (4) Å, b = 10.571 (2) Å, c = 11.1788 (2) Å
α = 104.01 °, β = 96.89 (2) °, γ = 66.67 (2) °,
_{^{v = 968.0 (5) Å 3}} , Z = 1, D c = 1.75 g cm -3, R = 0.0757, R w = 0.0896
[0013]
Example 3: Carbon-carbon bond cleavage reaction of benzopinacol using the complex of the present invention

The complex of the present invention (7 mg, 0.01 mmol) obtained in Example 2 and benzopinacol (366 mg, 1.00 mmol) were reacted in toluene (10 ml) at 65 ° C for 1 day. ^{From 1} H NMR, it was confirmed that benzopinacol as a raw material disappeared, and benzhydrol and benzophenone were quantitatively generated. Water was added to the reaction mixture, and the product was extracted with ether and separated by TLC. The yield of benzhydrol (170 mg, 0.92 mmol) was 92%, and the yield of benzophenone (164 mg, 0.90 mmol) was 90%. When [(Cp ^* ) IrClH] ₂ , which is a raw material of the complex of the present invention, was used, the central carbon-carbon bond of pinacol was not cleaved.
[0014]
Example 4: Isomerization reaction of 1-hexene using the complex of the present invention The complex of the present invention (10 mg, 1.5 × 10 ⁻² mmol) obtained in Example 2 and 1-hexene (0.19 ml, 1 0.5 mmol) in heavy benzene (0.5 ml) at room temperature. ¹ H NMR confirmed that isomerization to 2-hexene had occurred. The reaction progressed slowly and after 3 weeks almost all 1-hexene was isomerized to 2-hexene.
Embedded image

[0015]
【The invention's effect】
The novel iridium complex of the present invention is useful as a catalyst for, for example, a carbon-carbon bond cleavage reaction of benzopinacols or isomerization of alkenes.
[Brief description of the drawings]
FIG. 1 is a diagram showing a structure of an iridium complex [(Cp ^* ) IrH] ₂ of the present invention.

Claims (5)

An iridium complex represented by the formula: [CpIrH] ₂ (wherein Cp represents a cyclopentadienyl-based ligand). The complex according to claim 1, wherein the cyclopentadienyl-based ligand is a pentamethylcyclopentadienyl ligand. The following formula (I): C (R ¹ ) (R ² ) (OH) —C (R ³ ) (R ⁴ ) (OH) (wherein R ¹ , R ² , R ³ , and R ⁴ are each Independently represents a substituted or unsubstituted aryl group, wherein the aryl groups represented by R ¹ and R ² may be bonded to each other, and / or the aryl groups represented by R ³ and R ⁴ are bonded to each other The compound represented by the following formula (II): CH (R ¹ ) (R ² ) (OH) may be treated in the presence of a catalytic amount of the iridium complex according to claim 1 or 2. Wherein R ¹ and R ² are as defined above and formula (III): R ³ —CO—R ⁴ (wherein R ³ and R ⁴ are as defined above). . The iridium complex according to claim 1 or 2, which is a catalyst for cleaving a pinacol carbon-carbon bond of an aryl pinacol. 3. The iridium complex according to claim 1, which is a catalyst for isomerization of an alkene.

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