Hiroaki Chikamatsu

Structure of torilin

Abstract The structure of torilin (1), C22H32O5, isolated from the seeds of Torilis japonica DC, has been established as a sesquiterpene ester of the guaiane series.

Microbial stereo-differentiating reduction of carbonyl compounds; proposed quadrant rule

The stereochemistry of the alcohols obtained from microbial reduction (Curvularia lunata and Rhodotorula rubra) of the cyclic ketones (1)–(8) with a wide variation in molecular framework has led to the formulation of a quadrant rule which provides information on the absolute configuration of the substrate ketone.

Preparation of a novel optically active 8,8′-bi-isoquinolyl and its co-ordination as a bridging ligand in rhodium(I) complexes

A novel optically active 7,7′-dimethoxy-8,8′-bi-isoquinolyl (5) with known absolute configuration has been prepared and has been found to co-ordinate to RhI as a bridging ligand in [RhCl(cod)]2[µ-(±)-(5)](6) and {Rh2(cod)2[µ-(+)-(5)]2}(CIO4)2(8)(cod = cyclo-octa-1,5-diene).

Microbial resolution and asymmetric oxidation related to optically active 1,2-bis(methoxyphenyl)ethane-1,2-diol

An efficient microbial resolution of 1,2-bis-(methoxyphenyl)ethane-1,2-diol (2) has been achieved by exposing the corresponding diacetate to Trichoderma viride(T. konigii); stereoselective epoxidation of allylic alcohols and oxidation of sulphides are achieved with ButOOH using Ti(OPri)4–optically active diols (2) as chiral catalysts.

Microbial stereo-differentiating reduction of the carbonyl groups located on the C2 axes of gyrochiral molecules

Stereochemistry of microbial reduction (Curvularia lunata and Rhodotorula rubra) of the gyrochiral ketones whose C2 axes coincide with the carbonyl axes was examined to reveal a remarkable enantiomer selectivity.

Microbial resolution and asymmetric reduction related to optically active 1,3-diphenylpropane-1,3-diol

An efficient microbial resolution of 1,3-diphenylpropane-1,3-diol (4) has been achieved by exposing the corresponding diacetate to Trichoderma viride; a reductive cleavage of chiral acetals (6) derived from (4) with hydride reagent (Br2AlH, Cl2AlH) affords optically active alcohols (8) of high enantiomeric purities.

Synthesis and chiral recognition of an optically active bis-crown ether incorporating a diphenanthrylnaphthalene moiety as the chiral centre

A novel optically active double-layered bis-crown ether (–)-(S,S)-(7) with a diphenanthrylnaphthalene moiety as the chiral centre has been prepared, and examination of its chiral recognition behaviour showed that (–)-(S,S)-(7) has a high enantiomer selectivity for 1,6-diphenylhexamethylene-1,6-diamine.

Pig liver alcohol dehydrogenase catalysed stereoselective reduction of cage-shaped ketones. Preparation of axially chiral (–)-(R)-adamantane-2,6-diol with high enantiomeric purity

In a study of the stereoselective reductions of various cage-shaped ketones catalysed by pig liver alcohol dehydrogenase (PLADH), a typical axially chiral diol, (–)-(R)-adamantane-2,6-diol 12a with high enantiomeric purity was prepared by asymmetric reduction of keto ester 11d; based on this a new, remarkable function of the active site of the enzyme, which serves to enhance the stereoselectivity of the reaction is suggested.

Enzymatic hydrolysis of 2,6-diacetoxybicyclo[3.3.1]nonane and 2,6-diacetoxy-3,3,7,7-tetramethylbicyclo[3.3.1]nonane; a facile synthesis of the optically active chiral subunit for crown ethers

Hydrolysis of 2,6-diacetoxybicyclo[3.3.1]nonane (5) using lipase from Candida cylindracea gave (+)-(1S,2R,5S,6R)-(4)[81% enantiomeric excess (e.e.)] and (–)-(1R,2S,5R,6S)-(5)[95% e.e.], and pig liver esterase-catalysed hydrolysis of 2,6-diacetoxy-3,3,7,7-tetramethylbicyclo[3.3.1]nonane (9) gave (–)-(1S,2R,5S,6R)-(7)(96% e.e.) and (+)-(1R,2S,5R,6S)-(9)(86% e.e.); the enantiomer recognition behaviour of the crown ethers (–)-(11) and (+)-(12) prepared from (–)-(3) and (+)-(7), respectively, has been examined.

The C2-ketone rule in Horse liver alcohol dehydrogenase (HLADH)-catalysed oxidation and reduction

The enantiomer selectivity of HLADH with respect to the racemic C2-ketone substrates (1), (3), (5), and (7) has been examined, showing that the enzyme exhibits a remarkable selectivity which is opposite to that indicated by the microbial C2-ketone rule for Curvularia lunata and Rhodotorula rubra.