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N‐Heterocyclic Carbene Catalyzed Synthesis of δ‐Sultones via α,β‐Unsaturated Sulfonyl Azolium Intermediates
Author(s) -
Ungureanu Andrei,
Levens Alison,
Candish Lisa,
Lupton David W.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201504633
Subject(s) - carbene , sulfonyl , chemistry , electrophile , annulation , enantioselective synthesis , enol , organocatalysis , trimethylsilyl , catalysis , reactive intermediate , combinatorial chemistry , electrophilic addition , organic chemistry , alkyl
A limited array of reactive intermediates have enabled a wealth of discoveries in N‐heterocyclic carbene organocatalysis. In this study, the viability of α,β‐unsaturated sulfonyl azoliums as double electrophiles in new reactions is examined. Specifically, the (3+3) annulation of such species with the trimethylsilyl enol ethers of various 1,3‐dicarbonyl compounds has been developed. This reaction provides access to a range of novel unsaturated δ‐sultones (18 examples) in good yields (40–88 %) under mild reaction conditions. Mechanistic studies and the development of an enantioselective variant (55 % yield, 73:27 e.r.) support the intermediacy of an α,β‐unsaturated sulfonyl azolium species.