Highly efficient chemo- and enantioselective enzymatic resolution of (±)-methyl O-acetylmandelates

918-92

Remarkable chemo-, regio-, and enantioselectivity in lipase-catalyzed hydrolysis: efficient resolution of (±)-threo-ethyl 3-(4-methoxyphenyl)-2,3-diacetoxypropionate leading to chiral intermediates of (+)-diltiazem

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Selectivity paradigm in lipase reactions: correlating actual and observed regioselectivity in hydrolysis of unsymmetrical diacetates

The first simple method using labeling technique has been developed to confirm the actual and observed selectivities in the enzymatic hydrolysis of unsymmetrical diacetates and to measure the enzyme selectivity efficiency. The simple method consists of enzymatic hydrolysis of unsymmetrical diacetate followed by labeling of the hydroxyacetate formed with CD3COOD/DCC and enzymatic rehydrolysis of the labeled compound under the identical set of reaction conditions to estimate the amount of label retained by 1H NMR spectroscopy. The amount of label lost directly indicates the extent of regioselective action of the enzyme

Enantioselective enzymatic approach to (+)-and (-)-2-acetoxy/hydroxycyclopentanones

A new practical enzymatic approach to (+)- and (-)-2-acetoxy/hydroxycyclopentanones with 96-98% ee has been described via enzymatic hydrolysis of the meso-diacetate 2, Swern oxidation of the thus formed (±)-hydroxy acetates 3 and 4, followed by re-enzymatic resolution. Enantiomerically pure (+)- and (-)-2-hydroxycyclopentanones are in equilibrium with enediol 9 and slowly undergo racemisation, a process which could be arrested by protecting the hydroxyl group as the acetate