A Mechanistic Study on the Reaction of Iminothiadiazolines with Activated Acetylenes: Competitive Pathway through Hypervalent Sulfurane and Zwitterion
作者:Yohsuke Yamamoto、Tohru Tsuchiya、Masahide Ochiumi、Shin-ichi Arai、Naoki Inamoto、Kin-ya Akiba
DOI:10.1246/bcsj.62.211
日期:1989.1
The reaction of 3-aryl-5-benzoyl-2-imino-2,3-dihydro-1,3,4-thiadiazoles (6) with dimethyl acetylenedicarboxylate (4b) gave the corresponding thiazole (8) and benzoyl cyanide through sulfurane (B) by 1,3-dipolar cycloaddition and cis- (9) and trans-vinyl (10) compounds through zwitterion (C) by simple addition. Two types of addition reactions competed each other and the ratio of the two [R=B/C] depended solely on the solvent polarity (ET). Dibenzoylacetylene behaved similarly. Several iminothiazolines and iminothiadiazolines reacted with activated acetylenes and the selectivity for the two types of addition reactions for each system was shown to be affected by quite subtle balance of electron-withdrawing ability of each heterocycle.
3- 芳基-5-苯甲酰基-2-亚氨基-2,3-二氢-1,3,4-噻二唑(6)与乙炔二甲酸二甲酯(4b)通过 1,3-两极环加成反应(B)得到相应的噻唑(8)和苯甲酰基氰,通过简单加成反应(C)得到顺式(9)和反式乙烯基(10)化合物。两种加成反应相互竞争,两者的比例[R=B/C]完全取决于溶剂的极性(ET)。二苯甲酰基乙炔也有类似的表现。一些亚氨基噻唑和亚氨基噻二唑与活化的乙炔发生反应,结果表明,每个体系的两种加成反应的选择性受到每个杂环的电子吸收能力的微妙平衡的影响。