Cyclodehydration of cis–2-butene-1,4-diol with active methylene compounds catalyzed by a diphosphinidenecyclobutene-coordinated palladium complex

Abstract (π-Allyl)palladium triflate coordinated with 1,2-bis(4-methoxyphenyl)-3,4-bis(2,4,6-tri- t -butylphenylphosphinidene)cyclobutene (DPCB–OMe), [Pd(η 3 -C 3 H 5 )(DPCB–OMe)]OTf, efficiently catalyzes cyclodehydration of cis –2-butene-1,4-diol with active methylene compounds such as acetylacetone and ethyl acetoacetate in toluene in the presence of pyridine. The reactions can be performed in air, giving 2-vinyl-2,3-dihydrofurans in good to high yields.