Paolo Casati

On the steric course of baker's yeast mediated reduction of alkyl 4-azido- and 4-bromo-3-oxobutyrate. Synthesis of (R)- and (S)-carnitin

Abstract Bakers yeast reduction of ethyl 4-azido- and 4-bromo-3-oxobutyrate affords (3 R ) (8) and (3 S ) (2), respectively, in high optical purity.

Immobilized penicillinacylase: Application to the synthesis of the dipeptide aspartame

Abstract Immobilized penicillinacylase efficently catalyzes the conversion at pH 7.5 of N-phenacetyl aspartame ( 4 ) into aspartame ( 2 ) and phenylacetic acid.

Immobilized benzylpenicillin acylase: Application to the synthesis of optically active forms of carnitin and propranalol

The hydrolysis at pH 7.5 in the presence of immobilized benzylpenicillin acylase of the N-phenacetyl derivatives of the primary amines (3)-(5) affords the hydroxy amines (6)-(8), key intermediates in the synthesis of optically active forms of carnitin and propranalol, of ca. 0.4, 0.3 and 0.8 ee, respectively.

Substrate specificity and enantioselectivity of penicillinacylase catalyzed hydrolysis of phenacetyl esters of synthetically useful carbinols

Abstract Penicillinacylase from E.coli , immoblized on Eupergit C beads catalyzes the hydrolysis in water/CH 3 CN 10:1, at pH 7.5 and 23° C, of a set of O-phenylacetate esters of primary carbinols. The highest enantioselectivity is observed in the case of the 2,2-dimethyl-1,3-dioxolane-4-methanols structurally related to the penicillin (1) framework. Minor modifications of this basic structure are not altering the acceptability by the enzyme, but significantly decrease the enantioselectivity of the hydrolysis, as does the use of benzene as solvent and sepharose-bound enzyme.

Penicillinacylase and α-chymotrypsin catalysed hydrolysis of phenylacetate and phenylpropionate esters of 2,2-dimethyl-1,3-dioxolane-4-methanols

Penicillinacylase catalysed hydrolysis of phenylacetate esters affords the methanol derivatives (1)–(9), of moderate to high optical purity, whereas α-chymotrypsin acting on the phenylpropionate esters provides the alcohols of opposite configuration and low optical purity.