A New Annulation Reagent, 2-Oxo-3-alkenylphosphonates. Reactions with Carbonyl-Stabilized Carbanions or Silyl Enol Ethers Leading to Cyclohexenones.

E Wada, J Funakoshi, S Kanemasa

Index: Wada, Eiji; Funakoshi, Junji; Kanemasa, Shuji Bulletin of the Chemical Society of Japan, 1992 , vol. 65, # 9 p. 2456 - 2464

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Citation Number: 17

Abstract

The reactions of 2-oxo-3-alkenylphosphonates with carbonyl-stabilized carbanions directly lead to 2-cyclohexen-1-ones through a sequence of Michael reaction and intramolecular Horner–Emmons olefination. On the other hand, the Lewis acid-mediated reactions with silyl enol ethers produce 1, 5-diketones as Michael adducts, which then undergo cyclization on treatment with sodium hydride or triethylamine/zinc (II) bromide to afford 2-cyclohexen-1- ...