Isolation, synthesis and structure confirmation of the impurity in crude roflumilast product

Y Lin, P Huang, H Qi, L Chen, D Wang

Index: Lin, Yan; Huang, Peijun; Qi, Haofei; Chen, Ligong; Wang, Donghua Research on Chemical Intermediates, 2013 , vol. 39, # 7 p. 3111 - 3115

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Citation Number: 3

Abstract

Abstract An impurity was isolated from crude synthesized roflumilast and characterized by 1 H NMR, 13 C NMR, and HR-MS, which confirmed the structure as N-(3, 5-dichloropyrid-4-yl)- 4-difluoromethoxy-3-hydroxybenzamide. To further verify the structure, this compound was synthesized from 4-difluoromethoxy-3-hydroxybenzaldehyde. Comparison of the 1 H NMR, 13 C NMR, HR-MS, and the HPLC spectrum of the impurity and the authentic sample ...