A Highly Efficient and Enantioselective Access to Tetrahydroisoquinoline Alkaloids: Asymmetric Hydrogenation with an Iridium Catalyst
作者:Mingxin Chang、Wei Li、Xumu Zhang
DOI:10.1002/anie.201104476
日期:2011.11.4
Efficient and enantioselective: Using the iodine‐bridged dimeric iridium complex [Ir(H)[(S,S)‐(f)‐binaphane]}2(μ‐I)3]+I− (1) a wide range of tetrahydroisoquinoline alkaloids, including the substructure of the pharmaceutical drug solifenacin, were obtained with excellent enantioselectivities and high turnover numbers (see scheme).
The use of arene/Ru/TsDPEN catalysts bearing a heterocyclic group on the TsDPEN in the asymmetric transfer hydrogenation (ATH) of dihydroisoquinolines (DHIQs) containing meta- or para-substituted aromatic groups at the 1-position results in the formation of products of high enantiomeric excess. Previously, only 1-(ortho-substituted)aryl DHIQs, or with an electron-rich fused ring gave products with
displayed excellent enantioselectivity and good reactivity in the asymmetric hydrogenation of challenging 1-aryl-substituted dihydroisoquinoline substrates (full conversions, up to >99% ee, 4000 TON). The use of 40% HBr (aqueous solution) as an additive dramatically improved the asymmetric induction of these catalysts. This transformation provided a highly efficient and enantioselective access to chiral
Enantioselective, Copper-Catalyzed Alkynylation of Ketimines To Deliver Isoquinolines with α-Diaryl Tetrasubstituted Stereocenters
作者:Srimoyee Dasgupta、Jixin Liu、Clarissa A. Shoffler、Glenn P. A. Yap、Mary P. Watson
DOI:10.1021/acs.orglett.6b02787
日期:2016.12.2
An enantioselective, copper-catalyzedalkynylation of cyclic α,α-diaryl ketiminium ions has been developed to deliver isoquinoline products with diaryl, tetrasubstituted stereocenters. The success of this reaction relied on identification of Ph-PyBox as the optimal ligand, i-Pr2NEt as the base, and CHCl3 as the solvent. A broad scope and functional group tolerance were observed. Notably, the use of
A novel and efficient approach for the synthesis of amides has been developed through manganese dioxide promoted nondirected C-H activation of methylarenes under mild reaction conditions employing N-chloroamines as effective coupling partners.