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New oxidative cyclizations of 1,3,4,6‐tetraketones. Synthesis and structure of ( Z )‐2‐acyl‐5‐alkyl(aryl)‐1,4‐dioxaspiro[2.4]hept‐5‐en‐7‐ones
Author(s) -
Poje M.,
Sikirica M.,
Vicković I.
Publication year - 1983
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.5570200544
Subject(s) - chemistry , alkyl , aryl , tautomer , carbocation , ring (chemistry) , stereochemistry , crystal structure , medicinal chemistry , organic chemistry
Abstract Iodosobenzene diacetate oxidation of 1,3,4,6‐tetraketones 1a‐c yielded ( Z )‐2‐acyl‐5‐alkyl(aryl)‐1,4‐dioxa‐spiro[2.4]hept‐5‐en‐7‐ones (4a‐c) in addition to 2‐acyl‐6‐alkyl(aryl)‐3‐hydroxy‐4‐pyrones (3a‐c). The structure of new spiro‐heterocycles 4 was inferred from chemical and spectroscopic data, and the stereochemistry was fully defined by a single‐crystal X‐ray analysis. Alternative cyclization pathways can be rationalized as proceeding through carbocation intermediates derived from both forms of the ring‐chain tautomerism of 1,3,4,6‐tetraketones 1.