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Type: Artigo de periódico
Title: Diastereoselective reduction of E and Z alpha-alkoxyimino-beta-ketoesters by sodium borohydride
Author: Correa, IR
Moran, PJS
Abstract: The reduction of (Z)-alpha-alkoxyimino-beta-ketoesters, R1COC(=NOR3)CO2R2 (R-1=Me, Et, MeOCH2, Ph; R-2=Me, Et, PhCH2, R-3=Me, PhCH2) with NaBH4/THF-MeOH at 0 degrees C gave the corresponding (Z)-alpha-alkoxyimino-beta-hydroxyesters in 72-85% yield while the E isomers gave a mixture of corresponding (Z)- and (E)-2-alkoxyimino-1,3-diols in 71-85% yield. The (E)-alpha-alkoxyimino-beta-hydroxyesters were obtained in 71-85% yield when the reaction temperature was -72 degrees C. The C-13-NMR and IR spectra of (E)- and (Z)-alpha-oxyimino-beta-ketoesters and (E)- and (Z)-alpha-alkoxyimino-beta-ketoesters, were used for determination of E/Z configuration. The C-gamma signals in C-13-NMR of Z are shifted to higher field and the IR spectra of E isomers show a splitting of C=O ester band. (C) 1999 Elsevier Science Ltd. All rights reserved.
Subject: oximes
sodium borohydride
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Rights: fechado
Identifier DOI: 10.1016/S0040-4020(99)00897-2
Date Issue: 1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

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