Carbamoylimidazolium and thiocarbamoylimidazolium salts: novel reagents for the synthesis of ureas, thioureas, carbamates, thiocarbamates and amides
作者:Justyna A. Grzyb、Ming Shen、Chiaki Yoshina-Ishii、W. Chi、R.Stanley Brown、Robert A. Batey
DOI:10.1016/j.tet.2005.05.056
日期:2005.7
Carbamoylimidazolium salts act as efficient N,N-disubstituted carbamoylating reagents. These salts are readily prepared by the sequential treatment of secondary amines with N,N′-carbonyldiimidazole (CDI) and iodomethane. The carbamoylimidazolium salts are more efficient carbamoyl transfer reagents than the intermediate carbamoylimidazoles, as a result of the ‘imidazolium’ effect. Kinetic studies on
A highly efficient asymmetric hydrogenation of γ- and δ-ketoacids was developed by using a chiral spiro iridium catalyst (S)-1a, affording the optically active γ- and δ-hydroxy acids/lactones in high yields with excellent enantioselectivities (up to >99% ee) and turnover numbers (TON up to 100000). This protocol provides an efficient and practical method for enantioselective synthesis of Ezetimibe
Carbamoylimidazolium salts as diversification reagents: an application to the synthesis of tertiary amides from carboxylic acids
作者:Justyna A. Grzyb、Robert A. Batey
DOI:10.1016/j.tetlet.2003.08.026
日期:2003.9
preparation of tertiaryamides from carbamoylimidazolium salts and carboxylic acids is described. The transformation occurs at room temperature and under relatively mild conditions. The carbamoylimidazolium salts are obtained from the reaction of secondary amines with N,N′-carbonyldiimidazole, followed by methylation with methyl iodide. The utility of this reaction was demonstrated in the formation of Weinreb
Decarboxylative 1,4-Addition of α-Oxocarboxylic Acids with Michael Acceptors Enabled by Photoredox Catalysis
作者:Guang-Zu Wang、Rui Shang、Wan-Min Cheng、Yao Fu
DOI:10.1021/acs.orglett.5b02392
日期:2015.10.2
Enabled by iridium photoredoxcatalysis, 2-oxo-2-(hetero)arylacetic acids were decarboxylatively added to various Michael acceptors including α,β-unsaturated ester, ketone, amide, aldehyde, nitrile, and sulfone at room temperature. The reaction presents a new type of acyl Michael addition using stable and easily accessible carboxylicacid to formally generate acyl anion through photoredox-catalyzed
Direct amide formation from unactivated carboxylic acids and amines
作者:C. Liana Allen、A. Rosie Chhatwal、Jonathan M. J. Williams
DOI:10.1039/c1cc15210f
日期:——
The directcoupling of unactivated carboxylicacids with amines can be performed in toluene 110 degrees C in the absence of catalyst. The use of simple zirconium catalysts at 5 mol% loading gave amide formation in as little as 4 h.