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Silver‐Catalyzed Amidiniumation of Alkynes: Isolation of a Silver Intermediate, Synthesis of Enamine Amido Carbene Precursors, and an Unprecedented Umpolung of Propiolamide
Author(s) -
Lv Shichang,
Wang Jiwei,
Zhang Caiyun,
Xu Sheng,
Shi Min,
Zhang Jun
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201508221
Subject(s) - umpolung , carbene , chemistry , enamine , catalysis , substrate (aquarium) , organometallic chemistry , combinatorial chemistry , organic chemistry , medicinal chemistry , polymer chemistry , oceanography , nucleophile , geology
A silver‐catalyzed amidiniumation of N‐propiolic formamidines for the synthesis of novel enamine amido carbene precursors is reported. Isolation of a first silver intermediate in silver‐catalyzed amidiniumation of alkynes and other organogold intermediates supports our proposed mechanisms. Several control experiments reveal the unexpected effects of both HOTf and substrate substituents on the choice of either a π or σ,π silver activation mode and the cyclization fashion. Bis(hydroxyimidazol)ium salts were obtained through an unprecedented umpolung of propiolamides. The byproduct Ag 2 O as either an oxidant or silver source promotes the syntheses of N‐heterocyclic carbene (NHC) precursors or Ag/NHC complexes.