Reactions of acceptor substituted thiophene-1,1-dioxides with cyclopentadiene: control of selectivity by substitution
作者:Andrew M. Moiseev、Daniil D. Tyurin、Elizabeth S. Balenkova、Valentine G. Nenajdenko
DOI:10.1016/j.tet.2006.02.005
日期:2006.4
Diels–Alder reactions of thiophene-1,1-dioxides with strong electron withdrawing groups (EWG) were studied experimentally and theoretically. Thiophene-1,1-dioxides with two strong EWG behave as dienophiles and regio- and stereoselectively react with cyclopentadiene to give [2+4] cycloadducts 2a–c, which are derivatives of benzothiophene. In contrast, thiophene-1,1-dioxides with one EWG behave as dienes
通过实验和理论研究了具有强吸电子基团(EWG)的噻吩-1,1-二氧化物的Diels-Alder反应。具有两个强EWG的噻吩-1,1-二氧化物表现为亲二烯体,与环戊二烯进行区域和立体选择性反应,生成[2 + 4]环加成物2a – c,它们是苯并噻吩的衍生物。相反,具有一个EWG的噻吩-1,1-二氧化物在逆电子需求Diels-Alder反应中表现为二烯,生成二氢-1 H-茚衍生物。还证明了加合物2a – c的应付[3,3]-σ重排。MP2计算成功地合理化了这些环加成反应的对比区域选择性。