Unexpected Ring Enlargement of 2-Hydrazono-2,3-dihydro-1,3-thiazoles to 1,3,4-Thiadiazines
作者:Wolf-Diethard Pfeiffer、Klaus-Dieter Ahlers、Ashot S. Saghyan、Alexander Villinger、Peter Langer
DOI:10.1002/hlca.201300077
日期:2014.1
α‐bromoacetophenone can result in the formation of isomeric 1,3,4‐thiadiazines and two different thiazoles. We studied the use of 4‐methyl‐ and 4‐ethylthiosemicarbazide as dinucleophilic building blocks. In this context, we observed an unprecedented rearrangement of a 2‐hydrazono‐2,3‐dihydrothiazole to a 1,3,4‐thiadiazine. While ring contractions of 1,3,4‐thiadiazines to thiazoles are quite common, ring enlargements
硫代氨基脲与α-溴乙酰苯的环化可导致形成1,3,4-噻二嗪异构体和两种不同的噻唑。我们研究了使用4-甲基和4-乙基硫代氨基脲作为双亲核基石。在这种情况下,我们观察到了前所未有的2-肼基-2-2,3-二氢噻唑重排为1,3,4-噻二嗪的过程。1,3,4-噻二嗪对噻唑的环收缩很常见,而环的扩张则是新的。反应过程取决于底物的取代方式。