Direct Amidation of Carboxylic Acids through an Active α-Acyl Enol Ester Intermediate
作者:Xianjun Xu、Huangdi Feng、Liliang Huang、Xiaohui Liu
DOI:10.1021/acs.joc.8b00819
日期:2018.8.3
The development of a highly efficient and simple protocol for the direct amidation of carboxylic acids is described employing ynoates as novel coupling reagents. The transformation proceeds in good to excellent yields via in situ α-acyl enol ester intermediatesformation under mild reaction conditions. This useful method has been demonstrated for a range of substrates to provide a succinct access to
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
Microwave-acceleration of Carboxamides Formation Using Water Soluble Condensing Agent DMT-MM or DCC
作者:Nam-Sook Cho、Hye-Jin Jeon、Dong-Uk Heo
DOI:10.5012/jkcs.2012.56.5.658
日期:2012.10.20
reactions involving less reactive secondary and primary amines with acid in the presence of DMT-MM. We also compared the effectiveness of dicyclohexylcarbodiimide (DCC), a well-known condensing reagent, when coupled with microwave irradiation versus classical thermal methods. The reactions were performed by dissolving amines, carboxylic acids, and the condensing agent in solvent, followed by irradiation
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