Development of a scalable synthetic process for selective bromination of 4-methyl-3, 7-substituted coumarins

X Li, N Jain, RK Russell, R Ma, S Branum…

Index: Li, Xun; Jain, Nareshkumar; Russell, Ronald K.; Ma, Robert; Branum, Shawn; Xu, Jiayi; Sui, Zhihua Organic Process Research and Development, 2006 , vol. 10, # 2 p. 354 - 360

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Citation Number: 14

Abstract

The hydroxyl-protected coumarin derivatives 6a-e of 4-methyl-3-(2, 4-dihydroxyphenyl)-7- hydroxycoumarin (4) are key intermediates in the synthesis of unsymmetrical benzopyranobenzopyran compounds, a novel series of selective estrogen receptor modulators (SERMs). Free radical bromination of the 4-methyl group on 7-acetoxy-3-[(2, 4- diacetoxy) phenyl]-4-methylcoumarin (6a) with NBS resulted in incomplete reactions and ...