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Title: Mechanistic studies on the catalytic asymmetric Mannich-type reaction with dihydroisoquinolines and development of oxidative Mannich-type reactions starting from tetrahydroisoquinolines. Author: Dubs C, Hamashima Y, Sasamoto N, Seidel TM, Suzuki S, Hashizume D, Sodeoka M. Journal: J Org Chem; 2008 Aug 01; 73(15):5859-71. PubMed ID: 18578499. Abstract: 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 iminium ion via alpha-fragmentation. The iminium ion was also accessible via oxidation with DDQ as an oxidant, and a catalytic asymmetric oxidative Mannich-type reaction was achieved with tetrahydroisoquinolines (THIQs) as starting materials. This oxidation protocol was applicable to N-acryloyl-protected THIQs, allowing the efficient synthesis of optically active tetrahydrobenzo[a]quinolizidine derivatives via intramolecular Michael reaction.[Abstract] [Full Text] [Related] [New Search]