Eryka Guibé-Jampel

Stereoselective pig liver esterase-catalyzed hydrolysis of rigid bicyclic meso-diesters: preparation of optically pure 4,7-epoxytetra- and hexa-hydrophthalides

Abstract The bicyclic and rather rigid meso-diesters 1 - 3 have been found to be good substrates for pig liver esterase. The half-esters obtained have been converted to either one of the enantiomers of tricyclic lactones, of potential value for natural product synthesis.

Enzymatic resolution of racemic lactones

Abstract PPL, HLE or PLE enzymatic resolution of racemic γ, δ and e-lactones gives optically active lactones (ee: 60 to 90%).

Lipase-catalysed esterification of some α-D-glucopyranosides in dry media under focused microwave irradiation

Immobilized Candida antarctica lipase (Novozym 435)-catalysed esterifications of methyl α-D-glucopyranoside 1,α-D-glucose 2 and α,α-trehalose 3 with dodecanoic acid in dry media under focused microwave irradiation and classical heating conditions are described, under the same conditions of time and temperature. The advantages of performing the reactions in the microwave reactor are evident in all cases either in terms of yields and (or) purities of products.

1-Cyano-4-dimethylamino-pyridinium salts: new water-soluble reagents for the cyanylation of protein sulphydryl groups

1-Cyano-4-dimethylaminopyridinium perchloroate or fluoroborate rapidly react with thiols in neutral or acidic medium: in 11 min at pH 3·6, 98% of the catalytic activity of papain is inhibited; cysteine residues nos. 7 and 19 of the reduced B-chain of bovine insulin are quantitatively cyanylated at pH 3·5, then the N-peptide bonds are selectively cleaved at pH 9·5.

Enantioselective hydrolysis of racemic diesters by porcine pancreatic lipase

Porcine pancreatic lipase catalysed hydrolysis of dimethyl succinates, aspartates, and glutamate provides (R) and (S) methyl esters enantioselectively.

Selectivity in the transesterification of esters by supported enzymes

Abstract The regio and enantioselectivities of the transesterification of racemic dimethyl esters by supported enzymes in absence of solvent are studied: preparations of chiral succinates and N-acetyl aminoesters are reported.

A water-soluble agent for the t-butoxycarbonylation of amines

4-Dimethylamino-1-t-butoxycarbonylpyridinium chloride is a stable compound which reacts with amino-acid sodium salts in aqueous solution: at 25 °C the reaction is very fast and BOC = amino-acids (BOC = t-butoxycarbonyl) are isolated in good yields by solvent extraction.

ENZYMATIC GLYCOSIDATIONS IN DRY MEDIA ON MINERAL SUPPORTS

Abstract Preparation of 4-hydroxybutyl-β-D-glucoside was achieved by reversed hydrolysis from glucose using almond-β-glucosidase impregnated on mineral supports, while 4-hydroxybutyl-α-D-glucoside was obtained from glucose or by one-pot starch hydrolysis followed by glucosidation catalysed by γ-amylase (amyloglucosidase) from Rhizopus mold on celites. The influence of the support nature and of water activity were investigated in order to shift the equilibrium towards glycosidation.

An alkali-labile substituted benzyloxycarbonyl amino-protecting group

4-Isopropyloxycarbonyloxybenzyloxycarbonyl, Z(4-PriOCO), a new amino-protecting group stable under the conditions which cause cleavage of the t-butoxy-carbonyl and 2-(p-biphenylyl)isopropyloxycarbonyl groups, can be removed in a slightly alkaline medium via a 1,6-elimination, by hydrogenolysis, or by HBr in acetic acid.

Lipase catalyzed resolution of chiral acids or alcohols using mixed carboxylic-carbonic anhydrides

Abstract Mixed carboxylic-carbonic anhydrides are efficient irreversible acyl transfer reagents for lipase catalyzed esterification in organic media, and can be used for the resolution of chiral carboxylic acids or alcohols.