35018-63-4Relevant articles and documents
Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
supporting information, p. 1618 - 1629 (2021/01/25)
Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
Instantaneous low temperature gelation by a multicomponent organogelator liquid system based on ammonium salts
Velázquez, Daniel García,Díaz, David Díaz,Ravelo, ángel Gutiérrez,Tellado, José Juan Marrero
supporting information; experimental part, p. 7967 - 7973 (2009/02/02)
A new synergistic multicomponent organogelator liquid system (MOGLS) was discovered during the standard protocol of tartaric acid-mediated racemic resolution of (±)-trans-1,2-diaminocyclohexane. The MOGLS is formed by a 0.126 M methanolic solution of (1R,2R)-(+)-1,2-diaminocyclohexane L-tartrate and 1 equiv of concentrated hydrochloric acid. Nonreversible gelation of oxygenated and nitrogenated solvents occurs efficiently at low temperature. Several features make this system unique: (1) it is a multicomponent solution where each of the five components is required for the organogelation property; (2) the multicomponent organogelator liquid system (MOGLS) is formed by simple, small, and commercially available chiral building blocks dissolved in a well-defined solvent system (MeOH/HCl/H2O); (3) the chiral building blocks are easily amenable for further modifications in structure-property relationship studies; (4) the gelation phenomenon takes place efficiently at low temperature upon warming up the isotropic solution, conversely to the typical gel preparation protocol (gel formation upon cooling down the isotropic solution); (5) the formed organic gels are not thermoreversible in spite of the noncovalent interactions that hold the 3D-fibrillar network together.
De novo synthesis of tamiflu via a catalytic asymmetric ring-opening of meso-aziridines with TMSN3
Fukuta, Yuhei,Mita, Tsuyoshi,Fukuda, Nobuhisa,Kanai, Motomu,Shibasaki, Masakatsu
, p. 6312 - 6313 (2007/10/03)
An asymmetric ring-opening reaction of meso-aziridines with TMSN3 was developed using a catalyst prepared from Y(OiPr)3 and chiral ligand 2 in a 1:2 ratio. Excellent enantioselectivity was realized from a wide range of substrates with a practical catalyst loading. The products were efficiently converted to enantiomerically enriched 1,2-diamines, which are versatile chiral building blocks for pharmaceuticals and chiral ligands. This reaction was applied to a catalytic asymmetric synthesis of Tamiflu, a very important anti-influenza drug containing a chiral 1,2-diamino functionality. Copyright
