The Steric Effects of Alkyl Groups on the N–H Stretching Vibrations and the Rotational Isomerism of Alkylureas
作者:Yoshiyuki Mido、Tamotsu Gohda
DOI:10.1246/bcsj.48.2704
日期:1975.10
of the trans N–H band. It was also observed that the larger the effective size of the R′ group on R2UR′ is, the stronger the intensity of the additional band becomes. It was concluded, in connection with the rotational isomerism of dialkylureas, that the additional band arises from a form in which the N–H group is out of the skeletal plane.
Ureaderivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable
Organocatalyzed synthesis of ureas from amines and ethylene carbonate
作者:Francesco Saliu、Bruno Rindone
DOI:10.1016/j.tetlet.2010.09.107
日期:2010.12
A new solventless method for the synthesis of symmetrical and unsymmetrical ureas, starting fromethylenecarbonate and amines, is reported. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene(TBD) and thioureas have been found to be efficient organocatalysts for this reaction.
Chemo- and regio-selective amidation of indoles with isocyanates using borane Lewis acids
作者:Ayan Dasgupta、Michael G. Guerzoni、Nusaybah Alotaibi、Yara van Ingen、Kaveh Farshadfar、Emma Richards、Alireza Ariafard、Rebecca L. Melen
DOI:10.1039/d2cy01441f
日期:——
amide/urea functionality using mild, catalytic reaction protocols has always been an important challenge, as functionalised amides and urea derivatives are important scaffolds in medicinal chemistry. Herein we report a facile and mild catalytic reaction protocol towards the amidation of N-methyl indoles/pyrroles (17 examples, yields up to 58%) using B(C6F5)3 (30 mol%). Moreover, our investigation revealed