The synthesis of pyridothiazepines has been achieved via a 1,5‐dipolarcycloadditionreaction between pyridinium 1,4‐zwitterionic thiolates and activated allenes conducted under thermal conditions. Meanwhile, a ring‐contraction reaction of the resulting pyridothiazepine derivatives via the extrusion of 3‐thioxoacrylates has also been described.
<i>Cinchona</i> Alkaloid Catalyzed Enantioselective [4 + 2] Annulation of Allenic Esters and <i>in Situ</i> Generated <i>ortho</i>-Quinone Methides: Asymmetric Synthesis of Functionalized Chromans
作者:Yu-Hua Deng、Wen-Dao Chu、Xiang-Zhi Zhang、Xu Yan、Ke-Yin Yu、Liang-Liang Yang、Hanmin Huang、Chun-An Fan
DOI:10.1021/acs.joc.7b00370
日期:2017.5.19
A novel enantioselective [4 + 2] annulation of the allenoates having a unique positive ortho-effect with in situ generated ortho-quinone methides has been developed under the catalysis of Cinchonaalkaloid. This chiral amine-catalyzed reaction provides an alternative route to asymmetric catalytic construction of synthetically interesting, highly functionalized chiral chromans in good to excellent