A Practical and Efficient Process for the Preparation of Tazarotene

We describe an efficient process for the preparation of tazarotene starting from 4,4-dimethyl-6-bromothiochromane S-oxide
(9), 2-methyl-3-butyn-2-ol (10), and 6-chloronicotinic acid ethyl
ester (8). Our synthetic pathway compares favorably over the
previously reported procedures since tazarotene was prepared
straightforwardly using cheap reagents and without the employment of hazardous organometallic compounds. The process
is based on the use of sulfoxide 9 as key starting material. The
C-15 framework of the target was built up by means of two
different approaches based on a palladium-mediated coupling
reaction. The molecular structure of compound has been
confirmed by X-ray crystallography.