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Synthesis and reactivity of spiro[1,3,4-thiadiazoline-2,4′-thioflavans] and analogues

✍ Scribed by László Somogyi

Publisher
Journal of Heterocyclic Chemistry
Year
2009
Tongue
English
Weight
298 KB
Volume
46
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

magnified image

Racemic thioflavanone (thio)acylhydrazones undergo transformation into racemic 3‐acetylspiro[1,3,4‐oxa(thia)‐diazoline‐2,4′‐thioflavans] with trans O(1) or S(1) and Ph(2′eq) under acetylating conditions. Conjugation between the ethylenic bond and sp^2^ C(4) in thioflavones encumber both the formation of (thio)acylhydrazones and their subsequent spirocyclization. On the other hand, subsequent dehydrogenation of the thiopyran moiety of spiro compounds results in formation of sp^2^ C(4) and simultaneous degradation of the spirodiazoline ring. J. Heterocyclic Chem., 46, 399 (2009).

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