PROCESS FOR THE PREPARATION OF BIMATOPROST

It is provided a process for the preparation of bimatoprost, which comprises: a) reacting a compound of formula (III) with ethylamine in the presence of a suitable solvent; and b) deprotecting compound obtained in step a) to obtain bimatoprost, wherein R 1 is selected from (C 1 -C 16 )alkyl , (C 1 -C 16 )haloalkyl, (C 2 -C 16 )alkenyl, (C 2 -C 16 )haloalkenyl, (C 1 -C 16 )alkoxy(C 1 -C 16 )alkyl, aryl, (C 1 -C 16 )alkylaryl, allyl,-(CH 2 -CH 2 -O) n -CH 3 wherein n = 1, 2, 3 or 4, and -CH(O-CH 2 -CH 2 ) 2 ; R 2 is selected from H, (C 1 -C 16 )alkyl , (C 1 -C 16 )haloalkyl, (C 2 -C 16 )alkenyl, (C 2 -C 16 )haloalkenyl, (C 1 -C 16 )alkoxy(C 1 -C 16 )alkyl, aryl, (C 1 -C 16 )alkylaryl, allyl; or, alternatively, R 1 and R 2 taken together are selected from -CH 2 -CH 2 -CH 2 -, -CH 2 -CH 2 -, -O-CH 2 -CH 2 -, and -O-CH=CH-. There are also provided intermediates useful in such preparation process.