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
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
Catalytic Kinetic Resolution of Cyclic Secondary Amines
作者:Michael Binanzer、Sheng-Ying Hsieh、Jeffrey W. Bode
DOI:10.1021/ja209472h
日期:2011.12.14
The catalytic resolution of racemic cyclic amines has been achieved by an enantioselective amidation reaction featuring an achiral N-heterocyclic carbene catalyst and a new chiral hydroxamic acid cocatalyst working in concert. The reactions proceed at room temperature, do not generate nonvolatile byproducts, and provide enantioenriched amines by aqueous extraction.
Optically pure phosphoroselenoyl chloride was reacted with racemic amines to give phosphoroselenoic amides as two diastereomeric mixtures in high yields. The diastereomeric mixtures were separated by fractional recrystallization or by chromatography. Extrusion of the selenium atom from the separated amides led to diastereomerically pure phosphoramidites. The ability of the obtained amidites to act as optically active ligands was tested in the hydrogenation of an imine.
Design, synthesis and biological evaluation of novel podophyllotoxin derivatives bearing 4β-disulfide/trisulfide bond as cytotoxic agents
作者:Shi-Jun Zhu、Hua-Zhou Ying、Yan Wu、Ni Qiu、Tao Liu、Bo Yang、Xiao-Wu Dong、Yong-Zhou Hu
DOI:10.1039/c5ra12837d
日期:——
A novel series of C-4β-disulfide/trisulfide-containing podophyllotoxinderivatives were designed, synthesized, and biologically evaluated for their cytotoxic activities against human cancer cell lines, including KB (Mouth Epidermal Carcinoma Cells) and KB/VCR (Vincristine-resistant Mouth Epidermal Carcinoma Cells). Most of these compounds exhibited promising moderate to good cytotoxic activities. In