Impurities of tazarotene: isolation and structural characterisation.
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.
Brenna
Elisabetta
E
Dipartimento di Chimica, Materiali ed Ingegneria Chimica del Politecnico, Istituto CNR per la Chimica del Riconoscimento Molecolare, Politecnico di Milano, Via Mancinelli 7, I-20131 Milano, Italy. elisabetta.brenna@polimi.it
Frigoli
Samuele
S
Fronza
Giovanni
G
Fuganti
Claudio
C
Serra
Stefano
S
D004340:Drug Contamination; D009682:Magnetic Resonance Spectroscopy; D009539:Nicotinic Acids / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D012176:Retinoids
D009539:Nicotinic Acids; C086827:tazarotene; D012176:Retinoids