Synthesis of Dienol Ethers Using the Phosphine-Catalyzed Alkyne Isomerization Reaction

Abstract

A series of δ-alkoxy-substituted electron-deficient alkynes were isomerized to the corresponding dienol ethers using phosphine catalysis. Both Ph₃P and a polymer-supported phosphine were found to be useful in this context. This methodology represents a general procedure for the synthesis of ‘push-pull’ δ-alkoxy dienones.

organocatalysis - polymer-supported catalyst - alkyne isomerization - dienes - enol ethers - triphenylphosphine

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21

General Reaction Procedure
To a solution of 1 (1.0 mmol) in toluene (1 mL) was added Ph₃P or JJ-PPh₃ (0.2 mmol). The reaction vial was then shaken at 80 ˚C for 18 h. At this time, the reaction mixture was either concentrated and purified by silica gel chromatog-
raphy (for Ph₃P) or filtered and concentrated in vacuo (for JJ-PPh₃). All products 3 were characterized by ^¹H NMR and ^¹³C NMR spectroscopy.