A systematic study of reaction of heterocyclic enamines with electrophilic alkynes: A simple and efficient synthetic route to 2- pyridinone-fused heterocycles
The reaction of heterocyclic enamines with ethyl propiolate and diethyl acetylenedicarboxylate has been systematically studied. In contrast to their heterocyclic ketene aminal analogues, heterocyclic enamines reacted with electrophilic alkynes via the Michael addition pathway rather than the aza- ene reaction mechanism. In the presence of a strong base such as sodium ethoxide and sodium hydride, the resulting Michael addition products underwent cyclocondensation reaction readily to produce 2-pyridinone-fused heterocycles in good to excellent yield.
SYNTHESIS OF 5-OXOINDOLIZINE DERIVATIVES. II: REACTION OF THE ETHYL PYRROLIDIN-2-YLIDENEACETATE (AN ENAMINE ESTER) WITH ACYCLIC α,β-UNSATURATED CARBONYL COMPOUNDS
Synthesis of some 5-oxoindolizine derivatives using ethyl pyrrolidin-2-ylideneacetate (1) and acyclic α,β-unsaturated carbonyl compounds is described.The structure of Michael adducts, intermediates for 5-oxoindolizines, obtained by treatment of 1 with dimethyl acetylenedicarboxylate or methyl propiolate are discussed.
Nagasaka, Tatsuo,Inoue, Hitoshi,Hamaguchi, Fumiko
p. 1099 - 1107
(2007/10/02)
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