Mechanistic Studies on the Catalytic Asymmetric Mannich-Type Reaction with Dihydroisoquinolines and Development of Oxidative Mannich-Type Reactions Starting from Tetrahydroisoquinolines
作者:Christian Dubs、Yoshitaka Hamashima、Naoki Sasamoto、Thomas M. Seidel、Shoko Suzuki、Daisuke Hashizume、Mikiko Sodeoka
DOI:10.1021/jo800800y
日期:2008.8.1
Detailed mechanistic studies on our recently reported asymmetric addition reactions of malonates to dihydroisoquinolines (DHIQs) catalyzed by chiral Pd(II) complexes were carried out. It was found that an N,O-acetal was generated in situ by the reaction of DHIQ with (Boc)2O, and cooperative action of the Pd(II) complex as an acid−base catalyst allowed the formation of a chiral Pd enolate and a reactive
对我们最近报道的手性Pd(II)配合物催化的丙二酸酯与二氢异喹啉(DHIQs)的不对称加成反应进行了详细的机理研究。发现DHIQ与(Boc)2 O的反应原位生成了N,O-乙缩醛,作为酸碱催化剂的Pd(II)配合物的协同作用使得手性Pd烯醇盐形成和反应性亚胺离子通过α片段化 通过以DDQ作为氧化剂进行氧化也可以得到亚胺离子,并以四氢异喹啉(THIQs)为起始原料实现了催化不对称氧化曼尼希型反应。该氧化方案适用于N-丙烯酰基保护的THIQ,可通过分子内迈克尔反应有效合成光学活性的四氢苯并[ a ]喹啉二嗪衍生物。