Full details of the enantioselective reduction of cyclic meso-imides catalysed by an enantiopure oxazaborolidine derived from (S)-α,α-diphenylprolinol are reported. Treatment of the imides with borane in the presence of the catalyst led to a mixture of cis- and trans-hydroxylactams and, after subsequent ethanolysis, to the corresponding diastereomerically pure trans-ethoxylactams. The enantiomeric excesses were shown to be 68-94% by HPLC-determination. One example, in which the ethoxylactam was converted into the benzenesulfonyllactam, could be crystallized to >99% enantiomeric purity.
Oxazaborolidine catalysed enantioselective reduction of cyclic meso-imides
ROMAGNOLI, Romeo;
1997
Abstract
Full details of the enantioselective reduction of cyclic meso-imides catalysed by an enantiopure oxazaborolidine derived from (S)-α,α-diphenylprolinol are reported. Treatment of the imides with borane in the presence of the catalyst led to a mixture of cis- and trans-hydroxylactams and, after subsequent ethanolysis, to the corresponding diastereomerically pure trans-ethoxylactams. The enantiomeric excesses were shown to be 68-94% by HPLC-determination. One example, in which the ethoxylactam was converted into the benzenesulfonyllactam, could be crystallized to >99% enantiomeric purity.File in questo prodotto:
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