On the reaction of 1,3-diaza-2-azoniaallene salts with 1,3-butadienes and cumulenes
作者:Wolfgang Wirschun、Gerd-Michael Maier、Johannes C. Jochims
DOI:10.1016/s0040-4020(97)00283-4
日期:1997.4
1,3-Disubstituted triazenes 3 are oxidized with tert-butyl hypochlorite to N-chlorotriazenes 4, which at low temperatures with antimony pentachloride afford 1,3-diaza-2-azoniaallene salts 5 as reactive intermediates. Cations 5 undergo cycloadditions to one or both double bonds of 1,3-butadienes to furnish 4,5-dihydro-1H-1,2,3-triazolium salts (6a-k) (1,3-dipolar cycloaddition with inverse electron demand). With an allene, a butatriene, and a pentatetraene the 4,5-dihydro-1H-1,2,3-triazolium salts 6l-n were obtained. Some of the products undergo consecutive reactions to 1,2,3-triazolium salts (8a,b). The constitutions of 6n and 8b were secured by X-ray structural analyses. 4,5-Dihydro-1H-1,2,3-triazolium salts (6) and 1H-1,2,3-triazolium salts (8) are aza analogues of Arduengo's nucleophilic carbenes (imidazolidine-2-ylidenes, imidazole-2-ylidenes). (C) 1997 Elsevier Science Ltd.