A new synthetic access to 2-<i>N</i>-(glycosyl)thiosemicarbazides from 3-<i>N</i>-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors
作者:El Sayed H El Ashry、El Sayed H El Tamany、Mohy El Din Abdel Fattah、Mohamed R E Aly、Ahmed T A Boraei、Axel Duerkop
DOI:10.3762/bjoc.9.16
日期:——
mixtures of S- (major degree) and N-glycosides (minor degree) were obtained. Pure 3-N-(glycosyl)oxadiazolinethiones can also be selectively obtained from glycosylsulfanyloxadiazoles by the thermal S-->N migration of the glycosyl moiety, which is proposed to occur by a tight-ion-pair mechanism. Thermal S-->N migration of the glycosyl moiety can be used for purification of mixtures of S- or N-glycosides to obtain
5-(1H-吲哚-2-基)-1,3,4-恶二唑啉-2(3H)-硫酮的糖基化根据反应条件产生不同程度的S-和/或N-糖苷。S-糖苷是通过在碱性氧化铝中研磨恶二唑啉硫酮与酰化α-D-糖基卤化物而获得的,而3-N-(糖基)恶二唑啉硫酮是通过与HgCl(2)反应然后用α-加热所得氯汞盐选择性获得的。 D-糖基卤化物在甲苯中回流。使用Et(3)N或K(2)CO(3)作为碱,得到S-(主要程度)和N-糖苷(次要程度)的混合物。纯的3-N-(糖基)恶二唑啉硫酮也可以通过糖基部分的热S-->N迁移从糖基硫基恶二唑中选择性获得,这被认为是通过紧密离子对机制发生的。糖基部分的热S-->N迁移可用于纯化S-或N-糖苷的混合物以获得纯N-糖苷。在甲醇水溶液中用氨对相应的S-或N-糖苷进行氨解,进一步确认了它们的结构。而在S-糖苷中,糖基部分再次被裂解,3-N-(糖基)恶二唑啉硫酮显示恶二唑啉环开环(不影响糖基部分