PROCESS FOR THE PREPARATION OF ACETYLENIC RETINOID

摘要

A process for the preparation of acetylenic retinoid, ethyl-6-[2- (4,4- dimethylthiochroman-6-yl)ethynyl]nicotinate, a compound of formula 1,comprising, (a) cyclizing phenyl-3-methylbut-2-enylsulfide, a compound of formula 6, in presence of an acid selected from sulfuric acid or p-toluenesulfonic acid to yield 4,4-dimethylthiochroman, a compound of formula 2; (b)acetylating the compound of formula 2, to 4,4 -dimethyl-6-acetylthiochroman, a compound of formula 3; (c)(i) reacting the compound of formula 3 with hydrazine;(ii) reacting resultant product of step (i) with iodine; (iii) converting the resultant product of step (ii) to 4,4-dimethyl-6- ethynyl thiochroman, a compound of formula 4 and (d) reacting the compound of formula 4 with ethyl-6-halonicotinate, a compound of formula 5, wherein X is Cl or Br, in presence of cuprous halide, a transition metal and an inorganic base.