Montmorillonite K 10 and montmorillonite KSF as new and reusable catalysts for conversion of arnines to N-tert-butylcarbamates

Montmorillonite K 10 and montmorillonite KSF were found to be new and reusable catalysts for chemoselective conversion of an-lines to N-t-Boc derivatives at room temperature under solvent-free conditions without competitive formation of isocyanate, urea and N,N-di-t-Boc. Various aromatic, heteroaromatic and aliphatic amines afforded N-t-butylcarbamates in excellent yields on treatment with (Boc)(2)O after 5 min-2 h. Chiral amine and esters of a-amino acids afforded optically pure N-t-Boc derivatives in high yields. The catalytic efficiency of montmorillonite KSF was marginally inferior to that of montmorillonite K 10. (c) 2006 Elsevier B.V. All rights reserved.