CO2-catalysed carbamation of aminofunctional silanes

Under mild conditions (348 K), carbon dioxide (P-CO2 0.1 MPa) catalytically promotes the carbamation of the following industrially relevant aminofunct ional silanes: H2N(CH2)(3)Si (OMe)(3), H2N(CH2)(3)Si(OEt)(3) and H2N(CH2)(2 )NH (CH2)(3)Si(OMe)(3). These, upon reaction with dimethylcarbonate, are se lectively converted into the methyl carbamate esters MeO(O) CNH(CH2)(3)Si(O Me)(3), MeO(O)CNH(CH2)(3)Si (OEt)(3) and MeO(O)CNH(CH2)(2)NH(CH2)(3)Si (OMe )(3) respectively. Carbamate MeO(O)CNH (CH2)(3)Si(OEt)(3) is accompanied by MeO(O)CNH (CH2)(3)Si(OMe)(x)(OEt)(3-x) formed via transesterification of t he triethoxysilyl group by the co-produced methanol, The carbamation proces s is very selective and N-methylated species are formed in trace amounts. C onversely, the ureidofunctional silane H2NC(O)NH (CH2)(2)NH(CH2)(3)Si(OMe)( 3) shows a poor reactivity towards carbamation, and, under the above condit ions, N-methyl derivatives are preferably formed, Copyright (C) 2000 John W iley & Sons, Ltd.