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).
A convenient and general asymmetric transferhydrogenation of a wide array of 1-aryl-3,4-dihydroisoquinoline derivatives using a [RuIICl(η6-benzene)TsDPEN] complex in combination with a 5:2 HCOOH–Et3N azeotropic mixture as a hydrogen source was developed. Under mild reaction conditions, the described catalytic transformation secured a practical synthetic access to the corresponding valuable chiral
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
An efficient synthetic methodology has been developed to construct 1-aryl-3,4-dihydroisoquinoline derivatives. The reaction was performed under neutral conditions by a palladium-catalyzeddesulfitative carbon–carbon cross-coupling protocol.
4-dihydroisoquinolines undergo smooth acetoxylation/alkoxylation in the presence of 5 mol % Pd(OAc)2 and a stoichiometric amount of PhI(OAc)2 by means of C–H activation to produce the corresponding acetoxy- and alkoxy-1-aryl-3,4-dihydroisoquinoline derivatives respectively in good yields with high regioselectivity. It is a first example on oxidative functionalization of arenes tethered to dihydroisoquinoline moiety