Derivatives of furyl(diethoxyphosphoryl)acetic aldehyde in Wittig reaction

Abstract

Reactions of furyl(diethoxyphosphoryl)acetic aldehyde containing ester or cyano group in the furan ring with ethoxycarbonylmethylenetriphenylphosphorane has been shown to afford alkyl E-4-(furyl)-4-(diethoxyphosphoryl)but-3(2)-enoates. When treated with potassium tert-butoxide the mixture of alkyl E-4-(3-ethoxycarbonylfur-2-yl)-4-(diethoxyphosphoryl)but-2-enoate and -but-3-enoate gives a potassium salt of CHacid. Its acidifying results in a mixture of starting compounds with a larger amount of -but-3-enoate. Under analogous conditions the mixture of alkyl E-4-(2-ethoxycarbonylfur-3-yl)-4-(diethoxyphosphoryl)but-2-enoate and -but-3-enoate undergoes cyclization to a phosphorylated derivative of alkyl 7-hydroxybenzofuran-6-carboxylate. The cyclization of the mixture of alkyl E-4-(4-ethoxycarbonylfur-3-yl)-4-(diethoxyphosphoryl)but-2-enoate and -but-3-enoate gives analogous derivative of isobenzofuran.