摘要 |
<p>A process for the preparation of a compound of formula (I), wherein R1, and R2 are ortho or para substituents, independently selected from the group consisting of hydrogen, hydroxyl, C1-C6 alkyl; C1-C6 alkoxy, C7-C9 aralkoxy, C2- C7 alkanoyloxy, C1-C6 alkylmercapto, halo and trifluoromethyl; R3 is hydrogen or C1-C6 alkyl; R4 is hydrogen, C1-C6 alkyl, formyl or C2-C7 alkanoyl; n is one of the integers 0, 1, 2, 3 or 4; and the dotted line represents optional olefinic unsaturation; comprising hydrogenating a compound of formula (III), in the presence of a nickel or cobalt catalyst at a temperature of about 5 degree C to 25 degree C.</p> |