Tetrahedron letters

Transannular anti-Michael addition: formation of 4H-pyrazolo [5, 1-c] thiazines

YF Suen, H Hope, MH Nantz, MJ Haddadin, MJ Kurth

Index: Suen, Yat Fan; Hope, Hakon; Nantz, Michael H.; Haddadin, Makhluf J.; Kurth, Mark J. Tetrahedron Letters, 2006 , vol. 47, # 45 p. 7893 - 7896

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Citation Number: 7

Abstract

The reaction of 2-(diphenylmethylene) thietan-3-one (2) with 1, 2, 4, 5-tetrazines (3a–c) in KOH/MeOH/THF gives 4H-pyrazolo [5, 1-c] thiazines (7a–c). This novel condensation reaction proceeds via the intermediacy of an 8-(diphenylmethylene)-2H-1, 4, 5-thiadiazocin- 7 (8H)-one (5), which undergoes a multi-step rearrangement including a rare anti-Michael addition.