| 18096350 |
Brenna E, Frigoli S, Fronza G, Fuganti C, Serra S: Impurities of tazarotene: isolation and structural characterisation. J Pharm Biomed Anal. 2008 Feb 13;46(3):574-6. Epub 2007 Nov 17.
Two impurities showing structures 5 and 6 were isolated and characterised by means of NMR analysis, during the optimisation of a synthetic procedure to tazarotene. Impurity 5, i.e. ethyl 6-((4,4-dimethyl-4H-thiochromen-6-yl) ethynyl) nicotinate, was a by-product of the reduction of the intermediate sulfoxide 7 with PCl (3). Impurity 6, i.e. 1,4-bis (4,4-dimethylthiochroman-6-yl) buta-1,3-diyne, was due to a side reaction of the Sonogashira coupling. |
81(1,1,1,1) |