TRITHIASELENAPENTALENES AND DITHIASELENAPENTALENES FROM BENZYLIDENE-1,2-DITHIOLES AND HETEROCUMULENES

Deprotonation of the 5-aryl-3-benzyl-1 lambda(4),2-dithiol-1-ylium iod ides (6a-6d) obtained by reaction of the 1-aryl-4-phenylbutan-1,3-dion es (5a-5d) with hydrogen sulfide and iodine in ethanol gave the stable 5-aryl-3-benzylidene-3H-1, 2-dithioles (3a-3d), respectively. The dit hioles (3a-3d) underwent thermal cycloaddition reactions with isoselen ocyanates and isothiocyanates to give the 2-(substituted amino)-5-aryl -3-phenyl-6,6a lambda(4)-dithia-1-selenapentalenes (7a-7h) and the 2-( substituted amino)-5-aryl-3-phenyl-1,6,6a lambda(4)-trithiapentalenes (8a-8I), respectively. The dithioles (3a-3d) reacted with isocyanates to give the tuted-2-phenyl-2-(5-aryl-3H-1,2-dithiol-3-ylidene) acetami des (11a-11h). (C) 1997 John Wiley & Sons, Inc.