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Trimethylsilylcyanid als Umpolungsreagens, XVIII Nucleophile Acylierung von α‐Chlorcarbonyl‐Verbindungen – ein neuer und diastereoselektiver Zugang zu substituierten α,β‐Epoxyketonen
Author(s) -
Hünig Siegfried,
Marschner Claus
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230122
Subject(s) - chemistry , trimethylsilyl cyanide , nucleophile , umpolung , medicinal chemistry , deprotonation , silylation , trimethylsilyl , benzaldehyde , nucleophilic addition , organic chemistry , catalysis , ion
Trimethylsilyl Cyanide ‐ A Reagent for Umpolung, XVIII. ‐ Nucleophilic Acylation of α‐Chlorocarbonyl Compounds ‐ a Novel and Diastereoselective Approach to Substituted α,β‐fl‐Epoxy Ketones The addition products of trimethylsilyl cyanide and benzaldehyde ( 1a ), furfural ( 1b ), and α,β‐unsaturated aldehydes 2a‐c , respectively, react after deprotonation with α‐chloroaldehydes and ‐ketones 3a‐d . By 1,4‐ O,O ‐silyl rearrangement and cyanide elimination O ‐trimethylsilyl acyloins 4 and 9 , respectively, are formed. With fluoride, 4 and 9 react to α,β‐epoxy ketones 5 and 10 in high yield and with E/Z selectivities from 80:20 to >95: 5 . By this novel route even α,β‐unsaturated epoxy ketones ( 10 ) become available.