6083-47-2Relevant articles and documents
Process Development of the Copper(II)-Catalyzed Dehydration of a Chiral Aldoxime and Rational Selection of the Co-Substrate
Nonnhoff, Jannis,Gr?ger, Harald
, (2021/12/14)
The access towards chiral nitriles remains crucial in the synthesis of several pharmaceuticals. One approach is based on metal-catalyzed dehydration of chiral aldoximes, which are generated from chiral pool-derived aldehydes as substrates, and the use of a cheap and readily available nitrile as co-substrate and water acceptor. Dehydration of N-acyl α-amino aldoximes such as N-Boc-l-prolinal oxime catalyzed by copper(II) acetate provides access to the corresponding N-acyl α-amino nitriles, which are substructures of the pharmaceuticals Vildagliptin and Saxagliptin. In this work, a detailed investigation of the formation of the amide as a by-product at higher substrate loadings is performed. The amide formation depends on the electronic properties of the nitrile co-substrate. We could identify an acceptor nitrile which completely suppressed amide formation at high substrate loadings of 0.5 m even when being used with only 2 equivalents. In detail, utilization of trichloroacetonitrile as such an acceptor nitrile enabled the synthesis of N-Boc-cyanopyrrolidine in a high yield of 92 % and with full retention of the absolute configuration.
Half-Sandwich Iridium Complexes for the One-Pot Synthesis of Amides: Preparation, Structure, and Diverse Catalytic Activity
Fan, Xiao-Nan,Deng, Wei,Liu, Zhen-Jiang,Yao, Zi-Jian
, p. 16582 - 16590 (2020/11/13)
Several types of air-stable N,O-coordinate half-sandwich iridium complexes containing Schiff base ligands with the general formula [Cp*IrClL] were synthesized in good yields. These stable iridium complexes displayed a good catalytic efficiency in amide synthesis. A variety of amides with different substituents were obtained in a one-pot procedure with excellent yields and high selectivities through the amidation of aldehydes with NH2OHHCl and nitrile hydration under the catalysis of complexes 1-4. The excellent and diverse catalytic activity, mild conditions, broad substance scope, and environmentally friendly solvent make this system potentially applicable in industrial production. Half-sandwich iridium complexes 1-4 were characterized by NMR, elemental analysis, and IR techniques. Molecular structures of complexes 2 and 3 were confirmed by single-crystal X-ray analysis.
(Ar-tpy)RuII(ACN)3: A Water-Soluble Catalyst for Aldehyde Amidation, Olefin Oxo-Scissoring, and Alkyne Oxygenation
Joarder, Dripta De,Gayen, Subrata,Sarkar, Rajarshi,Bhattacharya, Rajarshi,Roy, Sima,Maiti, Dilip K.
, p. 8468 - 8480 (2019/07/03)
The synthetic chemists always look for developing new catalysts, sustainable catalysis, and their applications in various organic transformations. Herein, we report a new class of water-soluble complexes, (Ar-tpy)RuII(ACN)3, utilizing designed terpyridines possessing electron-donating and -withdrawing aromatic residues for tuning the catalytic activity of the Ru(II) complex. These complexes displayed excellent catalytic activity for several oxidative organic transformations including late-stage C-H functionalization of aldehydes with NH2OR to valuable primary amides in nonconventional aqueous media with excellent yield. Its diverse catalytic power was established for direct oxo-scissoring of a wide range of alkenes to furnish aldehydes and/or ketones in high yield using a low catalyst loading in the water. Its smart catalytic activity under mild conditions was validated for dioxygenation of alkynes to highly demanding labile synthons, 1,2-diketones, and/or acids. This general and sustainable catalysis was successfully employed on sugar-based substrates to obtain the chiral amides, aldehydes, and labile 1,2-diketones. The catalyst is recovered and reused with a moderate turnover. The proposed mechanistic pathway is supported by isolation of the intermediates and their characterization. This multifaceted sustainable catalysis is a unique tool, especially for late-stage functionalization, to furnish the targeted compounds through frequently used amidation and oxygenation processes in the academia and industry.
