United States Patent (19) 11 Patent Number: 5,756,790 Mukaiyama Et Al
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IIIUS005756790A United States Patent (19) 11 Patent Number: 5,756,790 Mukaiyama et al. 45 Date of Patent: May 26, 1998 (54) OPTICALLY ACTIVE COBALT (II) 58) Field of Search .................................. 556/32, 42, 45. COMPLEXES AND METHOD FOR THE 556/51, 130, 136, 146; 568/880, 885 PREPARATION OF OPTICALLY ACTIVE ALCOHOLS 56) References Cited 75) Inventors: Teruaki Mukaiyama, Tokyo; Kiyotaka PUBLICATIONS Yorozu, Kuga-gun; Takushi Nagata, Massonneau et al., Journal Of Organometallic Chemistry. Sodegaura; Toru Yamada, Sodegaura; vol. 288, pp. C59-C60 (1985). Kiyoaki Sugi, Sodegaura, all of Japan Primary Examiner-Porfirio Nazario-Gonzalez 73 Assignee: Mitsui Petrochemical Industries, Ltd., Attorney, Agent, or Firm-Sherman and Shalloway Tokyo, Japan 57 ABSTRACT The invention provides a method for preparing an optically 21 Appl. No.: 722,561 active alcohol comprising the step of reacting a ketone 22 Filed: Sep. 27, 1996 compound with a hydride reagent in the presence of an optically active metal compound. The resulting optically (30) Foreign Application Priority Data active alcohols are useful as intermediates for the synthesis Sep. 29, 1995 JP Japan .................................... 7.253477 of physiologically active compounds such as drugs and pesticides, functional materials such as liquid crystals, and (51) Int. Cl. ................... C07F 15/06; COTF 7700; raw materials for synthesis in fine chemistry. A novel C07C 29/14 optically active cobalt(II) complex useful as a catalyst is (52) U.S. Cl. ............................... 556/32; 556/42; 556/45; also provided. 556/51; 556/130; 556/136; 556/146; 568/880; 568/885 27 Claims, 2 Drawing Sheets U.S. Patent May 26, 1998 Sheet 2 of 2 5,756,790 DDSC(mW/min) N- O N w - He N O CN CY f) O N G CN S O H O 3. r S c) H f) w N O N O C O O ON O O O O O N Vr O O N m CN DSC(uW) 5,756,790 1. 2 OPTICALLY ACTIVE COBALT (II) handle hydride reagents as a reducing agent, we have found COMPLEXES AND METHOD FOR THE that the above-mentioned object can be attained by cata PREPARATION OF OPTICALLY ACTIVE lyzing reaction with an optically active metal compound. ALCOHOLS Making efforts to have an optically active metal com pound which is effective as a catalyst in the preparation of BACKGROUND OF THE INVENTION optically active alcohols, we have found a "novel optically 1. Field of the Invention active metal complex" such as an optically active cobalt This invention relates to a method for preparing optically complex. active alcohols as well as novel optically active metal Briefly stated, the present invention provides a method for complexes (cobalt (II) complexes). More particularly, it O preparing an optically active alcohol by reacting a ketone relates to a method for preparing optically active alcohols compound with a hydride reagent in the presence of an useful as intermediates for the synthesis of physiologically optically active metal compound. active compounds such as drugs and pesticides, functional Further, the present invention provides a method for materials such as liquid crystals, and raw materials for preparing an optically active alcohol from a ketone com synthesis in fine chemistry. It also relates to novel optically 15 pound with a hydride reagent in the presence of an optically active metal complexes which are useful as a catalyst in the active metal compound along with an alcohol compound. inventive method. Preferably, the optically active metal compound used as a 2. Description of the Related Art catalyst in the inventive method is an optically active cobalt As a general rule. alcohols are synthesized from corre (II) complex. More specifically, the optically active cobalt sponding ketones. A variety of methods are known for the (II) complex is of the following general formula (a): synthesis of alcohols. For the preparation of optically active alcohols from ketones, there are known several methods R. CR2 (a) including (1) utilization of enzymes and (2) utilization of R3 , K R3 chemical reaction. The enzyme utilizing method (1) typi cally uses baker's yeast (Saccharomyces cerevisiae) to pre 25 N. N pare optically active alcohols from ketones. With regard to the reduction of ketones with baker's yeast, it is generally R \ /* A. R4 believed that a hydride attacks a carbonyl group at its re O O R5 R5 plane to produce a S isomer of optically active secondary 30 alcohol in accordance with Prelog rule. This method, wherein each of R' and R', which are different, is a however, suffers from the problems that selectivity largely hydrogen atom, normal or branched alkyl group or aryl depends on the substrate and that only one of two enanti group, which may have a substituent, or two R' groups or omers can be synthesized. Known as the chemical reaction two R groups, taken together, may form a ring, and R. R' utilizing method (2) is hydrogenation using a BINAPruthe 35 and R may be the same or different, and are independently nium complex. This method has the problems that reaction selected from the group consisting of a hydrogen atom, must be done in a hydrogen atmosphere under a pressure as normal or branched alkyl group, aryl group, acyl group, and high as 20-100 atm. and preparation of a catalyst is cum alkoxycarbonyl group, which may have a substituent. bersome. In another aspect, the present invention provides a novel On the other hand, there is known a hydride reducing optically active metal (II) complex of the general formula method of reducing a ketone using an optically active metal hydride in the form of a metal hydride (as typified by (a). aluminum hydride and sodium boron hydride or diborane) modified with an optically active protonic compound. This R. R2 (a) R3 - R3 hydride reducing method, however, needs more than an 45 equivalent of the optically active protonic compound. Izuno, N N Corey, et al. recently proposed a catalytic asymmetric hydride reducing method using an aminoalcohol derived R V M M N A R4 from naturally occurring L-proline and aboran-sulfide com O O plex. Improvements in handling and cost are desired for this 50 method because the boran-sulfide complex is used as a R5 R5 reducing agent. wherein R. R. R. Rand Rare the same as in the formula (a) and M is an optically active transition metal compound SUMMARY OF THE INVENTION discussed below. Therefore, an object of the present invention is to provide 55 a method for preparing an optically active alcohol using a BRIEF DESCRIPTION OF THE DRAWTNGS hydride reducing agent which is easy to handle. The result FIG. 1 illustrates the structure as determined by X-ray ing optically active alcohol are useful as intermediates for diffractometry of an optically active cobalt(II) complex of the synthesis of physiologically active compounds such as formula (a-18) prepared in Example 66. drugs and pesticides, functional materials such as liquid FIG. 2 diagrammatically illustrates a differential scanning crystals, and raw materials for synthesis in fine chemistry. calorimetry curve of an optically active cobalt(II) complex Another object of the present invention is to provide a of formula (a-7) prepared in Example 67. novel optically active metal complex such as active cobalt complexes which is useful as a catalyst in the method for DETALED DESCRIPTION OF THE preparing an optically active alcohol. 65 INVENTION Making efforts to develop a method capable of synthe The method for preparing an optically active alcohol sizing optically active alcohols from ketones using easy-to according to the invention, referred to as an "inventive 5,756,790 3 4 substituent. Typical examples of the halogen atom include method," and the novel optically active cobalt(II) complex fluorine, chlorine and bromine. Typical examples of the are described in detail. normal or branched alkyl group include methyl, ethyl, The inventive method starts with a ketone compound isopropyl. n-propyl, t-butyl sec-butyl, and n-butyl groups. which is not critical insofar as it is a prochiral compound Cyclohexyl group is a typical example of the cycloalkyl having a carbonyl group in a molecule. Any desired ketone group. Typical examples of the aryl group include phenyl, compound may be selected in accordance with an end p-methoxyphenyl. p-chlorophenyl p-fluorophenyl, and optically active alcohol. naphthyl groups. Benzyloxy group is a typical example of Better results are obtained from the inventive method the alkoxy group. Typical examples of the acyl group when a ketone compound of the following general formula 10 include acetyl and propionyl groups. Typical examples of (b) is used as a starting material to produce a corresponding the alkoxycarbonyl group include methoxycarbonyl. optically active alcohol. ethoxycarbonyl. n-butoxycarbonyl, n-octyloxycarbonyl, and benzyloxycarbonyl groups. Typical examples of the amino O (b) group include dimethylamino and diethylamino groups. 15 Typical examples of the silyl group include trimethylsilyl 1. Rs and t-butylidimethylsilyl group. Letter n is equal to 0 or 1. R R7 and m is an integer of 1 to 4. When m is an integer of 2 to In formula (b), each of R. R. and R is a normal or 4. a corresponding plurality of R groups may be the same branched alkyl group, cycloalkyl group or aromatic group, or different. Alternatively, two R' groups, taken together, which may have a substituent. Typical examples of the may form a ring, or two R' groups, taken together, may normal or branched alkyl group represented by R. R. and form a ring. For example, the R' or R' groups are joined R include methyl, ethyl, n-propyl, and n-butyl groups. together through a linkage such as -(CH2)4- and -(CH2) Cyclohexyl is a typical example of the cycloalkyl group.