Thermolysis of β-hydroxysulfides bearing several heteroaromatics
摘要:
Thermolyses of beta-hydroxysulfides 2, bearing groups, such as 2-benzothiazolyl and 4-(4-methyl)-4H-1,2,4-triazolyI groups, were studied and found to afford the corresponding substituted styrenes 5 and hydroxy heteroaromatics in good yields, respectively. The product distribution change in the course of the thermolysis of 2a was also studied. The olefin products 5a were considered to be formed by the thermal desulfurization of the corresponding thiiranes 4a initially formed via the five-membered spiro intermediate 6a. (c) 2007 Elsevier Ltd. All rights reserved.
Benzothiazolyl 2-hydroxyethyl sulfoxide (1a) was found to afford bis[2-(2-oxobenzotiazolyl)-ethyl] disulfide (2a) in the presence of DBU at rt. 2a was formed by the condensation of corresponding sulfenic acid intermediate. Thermolyses of 1a in the presence of ethyl propiolate at 60-140 degrees C were carried out to succeed to trap sulfenic acid 6a as an intermediate. Trapping of 2-benzothiazolyloxyenthanesulfenic acid (6a) revealed that the thermal reaction proceeded via a five-membered spiro intermediate 5a.