Cyclic Seven??Membered Ketene Imines from Hindered 'Thiocarbonyl Ylides' and 2, 3??Bis (trifluoromethyl) fumaronitrile: Properties and Surprising Reactions

…, E Langhals, K Polborn, K Karaghiosoff

Index: Huisgen, Rolf; Langhals, Elke; Polborn, Kurt; Karaghiosoff, Konstantin Helvetica Chimica Acta, 2004 , vol. 87, # 6 p. 1426 - 1445

Full Text: HTML

Citation Number: 10

Abstract

Abstract 'Thiocarbonyl ylide'2B is accessible from 1, 1, 3, 3-tetramethylindanthione and CH 2 N 2, and subsequent N 2 extrusion at 40–50. In situ cycloaddition of the sterically hindered 2B with 2, 3-bis (trifluoromethyl) fumaronitrile ((E)-3) affords the isolable spirocyclic ketene imine 4B in high yield. X-Ray analysis discloses angle deformation, with ring strain being responsible for the high reactivity of 4B. In CDCl 3 at 40, 4B isomerizes to the trans- ...