Diels-Alder reactions of benzylidenecyanomethyl-1, 3-benzothiazoles and -1, 3-benzoxazoles 2a-f as 1-aza-1, 3-butadienes are described. The dienes 2, featuring the stabilized imine moieties by constituting heteroaromatic rings, react with both electron-deficient and electron-rich dienophiles 3a-c to give corresponding cycloadducts 4-6, regioselectively. The cycloadditions of the intramolecular systems 8a-d smoothly undergo via exo-transition state, stereoselectively affording polycyclic compounds 9a-d in good to excellent yields.
报道了苄叉
氰甲基-1,3-
苯并噻唑和-1,3-苯并噆唑2a-f作为1-氮-
1,3-丁二烯的Diels-Alder反应。这些二烯2通过构成杂芳香环而稳定了的
亚胺基团,与缺电子和富电子的二烯亲和体3a-c反应,选择性地生成相应的环加成产物4-6。内消旋体系的环加成反应8a-d通过外向过渡态顺利进行,立体选择性地得到
多环化合物9a-d,收率良好至优秀。