Allylidenetriphenylphosphorane as a bifunctional reagent: synthesis of cyclopentenones and. alpha.,. beta.-unsaturated ketones with [3-(alkoxycarbonyl)-2-ethoxy-2- …

…, Y Himeda, R Imashiro, Y Tanaka, I Ueda

Index: Hatanaka, Minoru; Himeda, Yuichiro; Imashiro, Ritsuo; Tanaka, Yasuhiro; Ueda, Ikuo Journal of Organic Chemistry, 1994 , vol. 59, # 1 p. 111 - 119

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Citation Number: 40

Abstract

When (3-(ethoxycarbonyl)-2-ethoxy-2-propenylidene) triphenylphosphorane (6) was allowed to react with a-bromo ketones 8a-d in dichloromethane in the presence of Cs2CO3 at room temperature, a [3+ 21 annulation occurred and led to the formation of the corresponding 2-ethoxycyclopentadienes Sa-d in excellent yields. Similarly, bromo thioester 8g underwent the annulation to give 44ethylthio)-cyclopentadiene Sg. Secondary ...