PROCESS FOR THE PREPARATION OF PHENYLCARBAMATES

This invention relates to a process for the preparation of an aminoalkyl phenyl carbamate compound of formula 1, (see formula I) wherein R1 and R2 independently are hydrogen or C1-6 alkyl; R3 and R4 are the same or different and each is a lower alkyl; or R3 and R4 together with the nitrogen to which they are attached form a cyclic moiety of a three to eight- member ring, with or without a hetero atom like nitrogen or oxygen; R5 and R6 independently are hydrogen, linear, branched or cyclic C1-6 alkyl, allyl, propargyl or benzyl; or R5 and R6 together with the nitrogen to which they are attached form a cyclic moiety of three to eight member ring, with or without a hetero atom like nitrogen or oxygen; the carbon center marked with "*" is racemic or enantiomerically enriched (R)- or (S)- configuration; and pharmaceutically acceptable addition salts, and crystalline and amorphous forms thereof comprising the steps of: i) converting an amine R5R6NH to a carbamoylimidazolium salt of formula 3 (see formula 3 wherein R5 and R6 are as defined above; X- is a counterion and R7 is an alkyl or aryl group; ii) reacting in a solvent at a controlled reaction temperature the compound of formula 3 with a compound of formula 4, (see formula 4) wherein R1, R2, R3, R4 and "*" are as defined above to give the compound of formula 1; and iii) isolating the compound of formula 1.