α-Diazo-β-hydroxy esters (3) prepared by condensation of aldehydes (1) with ethyl (lithio) diazoacetate (2) are reduced with 5% palladium over charcoal in methanol into the corresponding β-hydroxy esters (5) in high yield. This sequence is applied to a new synthesis of haemulcholic acid (14c), a (22S)-22-hydroxy bile acid from fish bile and its (22R)-epimer (14d). A convergent synthesis of (14c), a (22S)-22-hydroxy bile acid from fish bile and its (22R)-epimer (14d). A convergent synthesis of (14c) and (14d) involves, as a key step, the dirhodium (II) tetra-acetate conversion of (12) into the corresponding β-keto ester (13).
Reduction of alpha-Diazo-beta-Hydroxy Esters to beta-Hydroxy Esters: Application in one of two Convergent Syntheses of a (22 S)-22-Hydroxy Bile Acid from Fish Bile and its (22 R)-Epimer
PELLICCIARI, Roberto;NATALINI, Benedetto;
1985
Abstract
α-Diazo-β-hydroxy esters (3) prepared by condensation of aldehydes (1) with ethyl (lithio) diazoacetate (2) are reduced with 5% palladium over charcoal in methanol into the corresponding β-hydroxy esters (5) in high yield. This sequence is applied to a new synthesis of haemulcholic acid (14c), a (22S)-22-hydroxy bile acid from fish bile and its (22R)-epimer (14d). A convergent synthesis of (14c), a (22S)-22-hydroxy bile acid from fish bile and its (22R)-epimer (14d). A convergent synthesis of (14c) and (14d) involves, as a key step, the dirhodium (II) tetra-acetate conversion of (12) into the corresponding β-keto ester (13).File in questo prodotto:
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