90 3C/0.001 Torr) 23 b affords the products 25a-c in almost statistical I : 2: 1 distribution (67 % yield). If the distillation is conducted at 180 "C/26 mbar, the thermodynamically favored Z,Z isomer 25a predominates (56 % yield of 2 5 8 : 1 : 1 distribution). Apparently at least the second rearrangement step, 24 + 25, is reversible at higher temperatures.As anticipated, on treatment with tetracyanoethylene (TCNE) 25a reacts considerably faster to 26a than its stereoisomer 25b to the cycloadduct 26b.Isothiocyanate-substituted 1,3-butadienes can be used as well as the allenes 4 for the synthesis of thiazoles, but also for the preparation of other heterocycles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.