Synthesis of Urea Derivatives from CO₂ and Silylamines

Abstract

A series of thirty‐three N,N′‐diaryl, dialkyl, and alkyl‐aryl ureas have been prepared in pyridine or toluene by reaction of silylamines with CO2. This protocol is shown to provide facile access to 13C‐labeled ureas, as well as chiral and macrocyclic ureas. These reactions proceed through initial generation of the corresponding silylcarbamates, which subsequently react with silylamine under thermal conditions to afford the thermodynamically favored urea and disilyl ether.

Double Phosphinoboration of CO2: A Facile Route to Diphospha‐Ureas

“…[24] Based on the spectroscopy alone, the compound was formulated as Ph 2 PCO 2 Bpin 1 (Scheme 1). In this product of phosphinoboration of CO 2 ,t he newly formed PÀCb ondw as found to be 1.850(2) whereas the OÀBb ond was found to be 1.383(3) .T he slightly distorted trigonal-planar geometry at the centralc arbon atom results in aP -C-O angle of 111.12 (16)8,w hereas the CÀOd istances of 1.197(3) and 1.360(3) are consistent with formal double and single bonds, respectively. In this product of phosphinoboration of CO 2 ,t he newly formed PÀCb ondw as found to be 1.850(2) whereas the OÀBb ond was found to be 1.383(3) .T he slightly distorted trigonal-planar geometry at the centralc arbon atom results in aP -C-O angle of 111.12 (16)8,w hereas the CÀOd istances of 1.197(3) and 1.360(3) are consistent with formal double and single bonds, respectively.…”

“…Repetitiono ft he reactiona fforded X-ray quality crystals and the subsequentd iffractions tudy confirmed the formulation (Figure 1). In this product of phosphinoboration of CO 2 ,t he newly formed PÀCb ondw as found to be 1.850(2) whereas the OÀBb ond was found to be 1.383(3) .T he slightly distorted trigonal-planar geometry at the centralc arbon atom results in aP -C-O angle of 111.12 (16)8,w hereas the CÀOd istances of 1.197(3) and 1.360(3) are consistent with formal double and single bonds, respectively.…”

“…[11] In recent studies, ureas have been prepared from CO 2 and aliphatic amines exploiting transition-metal-based catalysts [12] or cesium-based catalysts. [16] In contrast to ureas, the phosphorus analogues,d iphosphaureas,( R 2 P) 2 CO are rare. [14] Interestingly, even thought he direct reactiono fC O 2 with amines [12c, 15] generally requires high pressure (14-140atm)a nd high temperature (130-170 8C), we have recently shown that judicious choiceo fs olventp romotes the reaction of CO 2 and silylamines to give silylcarbamates and ureas.…”

“…[14] Interestingly, even thought he direct reactiono fC O 2 with amines [12c, 15] generally requires high pressure (14-140atm)a nd high temperature (130-170 8C), we have recently shown that judicious choiceo fs olventp romotes the reaction of CO 2 and silylamines to give silylcarbamates and ureas. [16] In contrast to ureas, the phosphorus analogues,d iphosphaureas,( R 2 P) 2 CO are rare. The first example of ad iphospha-urea (R = Ph) was preparedi nlow yieldb yt he reaction of Ph 2 PSiMe 3 with phosgene at À110 8C.…”

Concise and Additive‐Free Click Reactions between Amines and CF3SO3CF3

“…[2] The production of urea derivatives from CO, CO 2 ,a nd other miscellaneous carbonylation reagents has also been implemented. [3,4] Moreover,c arbamoyl fluorides, whichr epresent another class of interesting compounds, have been applied as the pre-cursorso fh ypofluorite, isocyanates,c arbamate, N-fluoroalkylamines,a nd ureas, and as the starting materials for the synthesis of insecticides. [5,6] They can also be used as inhibitors of enzymes.…”