Makoto Kamezawa

Enantioselectivity of Candida antarctica lipase for some synthetic substrates including aliphatic secondary alcohols

Abstract Candida antarctica lipase (Novozym 435) showed good to high enantioselectivity in the acylation of aliphatic and aromatic secondary alcohols ( E = 38−166), and higher enantioselectivity in the hydrolysis of their corresponding acetates than other lipases tested, including lipases AY and MY ( Candida sp.) and lipases PS, AK and LIP ( Pseudomonas sp.).

An efficient novel synthesis of β-(azuleno[1,2-b]benzothienyl)- and β-(azuleno[2,1-b]benzothienyl)-α,β-unsaturated ketones by the tropylium ion-mediated intramolecular furan ring-opening reaction and X-ray investigation of methyl ketone derivative

Intramolecular reaction of 2-tropylio-3-(5-substituted 2-furyl)benzothiophenes (3), prepared from the corresponding 2-cycloheptatrienyl-3-(5-substituted 2-furyl)benzothiophenes (2), afforded the β-(azuleno[1,2-b]benzothienyl)-α,β-unsaturated ketones (4), which are otherwise difficult to obtain, in moderate yields. The reaction involves a ring-opening process of the furan ring by intramolecular attack of the tropylium ion onto the 2-position of the furan ring. Similarly, β-(azuleno[2,1-b]benzothienyl)-α,β-unsaturated ketones (8) were obtained from the corresponding 3-tropylio-2-(5-substituted 2-furyl)benzothiophenes (7) albeit in lower yields. The molecular and crystal structures of the methyl ketone derivative, 8a, are discussed on the basis of X-ray structure analysis.

BIOCATALYTIC PREPARATION OF CHIRAL ALCOHOLS BY ENANTIOSELECTIVE REDUCTION WITH IMMOBILIZED CELLS OF CARROT

The ability of immobilized cells of Daucus carota to reduce enantioselectively organic foreign substrates has been examined. The immobilized plant cells reduced, with excellent enantioselectivity, prochiral ketone substrates such as keto esters, aromatic ketones and heterocyclic aromatic ketones, leading to the corresponding chiral secondary alcohols with an enantiomeric purity of 52–99% ee in a chemical yield of 30–63%.

Enzymatic preparation of enantiomerically pure alkan-2- and -3-ols by lipase-catalysed hydrolysis with Pseudomonas cepacia in the presence of organic media

Pseudomonas cepacia lipase-catalysed hydrolysis of the acetates of racemic alkan-2- and -3-ols was carried out in the presence of organic media. Good to high enantioselectivity was observed in an acetone–water solvent system, the system leading to (R)-alcohols of 80–96% ee. Enantioselectivity can be affected by the presence of the double bond in the unsaturated acetate prepared from an alkenol. The increased enantioselectivity observed for an acetone–water reaction system was utilized in the synthesis of optically active natural products possessing alkan-2-ol skeletons, such as (2R,6R,10R)-6,10,14-trimethylpentadecan-2-ol, the natural form of the sex pheromone of Corcyra cephalonica, and (R)-sulcatol, an aggregation pheromone of ambrosia beetles.

Biocatalytic synthesis of (S)-2-tridecanyl acetate and (S)-2-pentadecanyl acetate, aggregation pheromone components ofDrosophila mulleri andD. busckii, by enantioselective hydrolysis with lipase

The two chiral pheromone acetates, (S)-2-tridecanyl acetate and (S)-2-pentadecanyl acetate, were synthesized with an enantiomeric excess (e.e.) of almost 100% byPseudomonas cepacia lipase-catalyzed hydrolysis of their corresponding racemic acetates in an acetone-water solvent system.

Chemoenzymatic synthesis of (+)-docosa-4,15-dien-1-yn-3-ol, a component of the marine sponge Cribrochalina vasculum, and confirmation of the structure and absolute configuration of the acetylenic alcohol, by lipase-catalysed biotransformations

The (4E,15Z)- and (4E,15E)-isomers of (+)-docosa-4,15-dien-1-yn-3-ol 1, isolated from the marine sponge Cribrochalina vasculum, were synthesized in highly enantiomerically pure form by lipase-mediated biotransformation with Novozym 435, and the structure of 1 from the natural product was proved to be (4E,15Z)-docosa-4,15-dien-1-yn-3-ol 1Z. The absolute configuration of C-3 in compound (+)-1Z was assigned as S on the basis of the conversion of (+)-1Z into (R)-(–)-docosan-3-ol 17, which was also prepared from oct-7-en-3-ol 12 via biotransformation with lipase Novozym.

CHEMOENZYMATIC SYNTHESIS OF (+)-(4E,15E)-DOCOSA-4,15-DIEN-1-YN-3-OL, A COMPONENT OF THE MARINE SPONGE CRIBROCHALINA VASCULUM

An acetylenic alcohol, (+)-(4E, 15E)-docosa-4,15-dien-1-yn-3-ol 1, isolated from the marine sponge Cribrochalina vasculum, was synthesized in highly enantiomerically pure form by lipase-catalysed transesterification with Novozym 435 (Candida antarctica).

PECHMANN REACTION OF RESORCINOL WITH METHYL ACETOACETATE. STRUCTURE OF A BY‐PRODUCT

Bei der Pechmann-Duisberg-Reaktion von Resorcin (I) mit Acetessigsauremethylester wird neben dem Cumarin (IIIa) das dimere Nebenprodukt (IVa) isoliert.