Kurt Laumen

Enzymatic esterification of glycerol I. Lipase-catalyzed synthesis of regioisomerically pure 1,3-sn-diacylglycerols

Regioisomerically pure 1,3-sn-diacylglycerols are conveniently prepared in high yields (>80%) and in large quantities by enzymatic esterification of glycerol in the presence of various 1,3-selective lipases(Chromobacterium viscosum, Rhizopus delemar, Rhizomucor miehei) and a variety of different acyl donors like free fatty acids, fatty acid alkyl esters and vinyl esters. All reactions are carried out in aprotic organic solvents of low water content, namelyn-hexane, diethyl ether or tBuOMe. The creation of an artificial interphase between the solvent-immiscible hydrophilic glycerol and the hydrophobic reaction media by the adsorption of glycerol onto a solid support prior to use was essential for the success of these transformations. The effects of reaction conditions and the regioselectivities of the lipases on the product yields are described in detail.

Enzymatic hydrolysis of prochiral cis-1,4-diacyl-2-cyc-lopentenediols: preparation of (1S,4R)-and (1R,4S)-4-hydroxy-2-cyclopentenylderivatives, versatile building blocks for cyclopentanoid natural products.

Abstract The enzymatic hydrolysis of prochiral diesters 1 was studied in presence of seven enzymatic systems, resulting in the enantioselective preparation of both enantiomeric series of chiral building blocks 2 - 4 and ent - 2 - 4 on a preparative scale.

Enantioselective hydrolysis of cis -1,2-diacetoxycycloalkanedimethanols:enzymatic preparation of chiral building blocks from prochiral meso -substrates.

Abstract The enzymatic hydrolysis of the prochiral title compounds (=1a) - (=f) in presence of porcine liver esterase (PLE) and lipase from porcine pancreas (PPL) was studied, resulting in the preparation of the chiral monoacetates (=2b) - (=f) with high (72–99%e.e.) enantiomeric purities.

Immobilized porcine liver esterase: a convenient reagent for the preparation of chiral building blocks.

Abstract A simple method for the effective, covalent, immobilization of porcine liver esterase ( PLE ) is described, and the application of this reagent for the preparation of chiral building blocks on a 50 – 500 mmol scale is demonstrated.

Lipase-catalyzed esterification of hydrophilic diols in organic solvents

SummaryThe direct, lipase-catalyzed esterification of hydrophilic diols in organic solvents was achieved by first adsorbing the hydrophilic, solvent immiscible substrate onto a solid support with high internal surface, namely silica gel and reacting the solid mixture with fatty acid vinyl esters in an appropriate organic solvent and in presence of an immobilized lipase fromMucor miehei (Lipozyme). Quantitative conversions of the acyl donors and very high reaction rates were observed in these transformations. Furthermore, mono- or diesters of these diols could be selectively produced by this method.

Enzymatic preparation of optically active cyanohydrin acetates

A series of cyanohydrin acetates (1)–(47) of widely varying structures, potential chiral building blocks for numerous synthetic applications, has been prepared in good chemical and often high optical yields by enzymatic hydrolysis of their racemic acetates in the presence of an ester hydrolase from Pseudomonas sp.

A highly selective ester hydrolase from Pseudomonas sp. for the enzymatic preparation of enantiomerically pure secondary alcohols; chiral auxiliaries in organic synthesis

A series of valuable chiral auxiliaries, (R)- and (S)-(1)–(11), have been prepared in high chemical and optical yields by enzymatic hydrolysis of their esters in the presence of a lipase from Pseudomonas sp.

Enantiomerically pure cyclohexanols and cyclohexane-1,2-diol derivatives; chiral auxiliaries and substitutes for (–)-8-phenylmenthol. A facile enzymatic route

A number of optically active cyclohexanol and cyclohexane-1,2-diol derivatives, chiral auxiliaries and substitutes for (–)- and (+)-8-phenylmenthol, have been prepared by enzymatic hydrolysis of their racemic acetates and chloroacetates in the presence of highly selective ester hydrolase from Pseudomonas sp.(SAM–II).

Enzymatic hydrolysis of (±)-trans-1,2-diacetozycycloalkanes. A facile route to optically-active cycloalkane-1,2-diols

The racemic title compounds were resolved conveniently into the enatiomers with high optical purities by enzymatic hydrolysis in the presence of porcine liver esterase.

Enzymic preparation of enantiomerically pure secondary alcohols. Ester synthesis by irreversible acyl transfer using a highly selective ester hydrolase from Pseudomonas sp.; an attractive alternative to ester hydrolysis

A series of secondary alcohols [(R)- and (S)-(1)–(3) and (5)–(9)] of interest as attractive chiral auxiliaries were prepared in high chemical and optical yields via enzymic esterification under essentially anhydrous conditions by employing a highly selective ester hydrolase from Pseudomonas sp. and vinyl acetate as acyl donor.