Premium
Regio‐ and stereochemistry of the photo‐ring contraction of 4‐pyrones
Author(s) -
Pavlik James W.,
Kirincich Steven J.,
Pires Richard M.
Publication year - 1991
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570280264
Subject(s) - chemistry , contraction (grammar) , stereochemistry , ring (chemistry) , organic chemistry , medicine
Irradiation of 2‐ethyl‐3‐methyl‐4‐pyrone 3 in aqueous solution led to the formation of trans ‐4‐ethyl‐5‐methy‐4,5‐dihydroxycyclopent‐2‐enone 4 and trans ‐2‐methyl‐3‐ethyl‐4,5‐dihydroxycyclopent‐2‐enone 5 . In the latter case 1 H nmr analysis confirmed the trans ‐configuration at C 4 and C 5 . These results are consistent with trapping of a photochemically generated oxabicyclohexenyl zwitterion by nucleophilic attack of both sides of the oxyally system along a path anti to the epoxide ring.