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Anomalous Effect of α,α,α‐Trifluoroacetophenone Derivatives on a Conjugated Umpolung Reaction: Enantioselective Direct Self‐Annulation of Enals Catalyzed by a Chiral Cyclophane‐type N‐Heterocyclic Carbene
Author(s) -
Ishida Yasuhiro,
Kawatsu Kunihiro,
Matsuoka Yuki,
Yamada Kuniyo,
Ikariya Ryuichi,
Sawayama Jun,
Hirao Shotaro,
Nishiwaki Nagatoshi,
Saigo Kazuhiko
Publication year - 2013
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201200153
Subject(s) - umpolung , chemistry , annulation , enantioselective synthesis , carbene , organocatalysis , combinatorial chemistry , catalysis , organic chemistry , stereochemistry , nucleophile
Do it yourself : A broadly applicable, enantioselective, direct self‐annulation of enals is presented. An N‐heterocyclic carbene derived from a chiral cyclophane‐type imidazolium salt catalyzes the self‐annulation of cinnamaldehyde derivatives to afford the corresponding γ‐butyrolactones with up to 99 % ee. The use of α,α,α‐trifluoroacetophenone derivatives as cocatalysts was essential to obtain satisfactory yields and enantioselectivity.