MANGANESE(III)-BASED FACILE SYNTHESIS OF 3-CYANO-4,5-DIHYDROFURANS AND 4-CYANO-1,2-DIOXAN-3-OLS USING ALKENES AND ACYLACETONITRILE BUILDING-BLOCKS

New 3-cyano-4,5-dihydrofurans and 4-cyano-1,2-dioxan-3-ols were altern atively synthesized in good yields by the oxidation of acylacetonitril e building blocks with manganese(III) acetate in the presence of alken es without any byproducts. The reaction at reflux temperature gave 3-c yano-4,5-dihydrofurans under an argon atmosphere, while 4-cyano-1,2-di oxan-3-ols were obtained at 23 degrees C under an air atmosphere excep t for the reaction of styrene with benzoylacetonitrile which afforded 2-cyano-1,4-diphenylbutane-1,4-dione, and the reaction of 1,1-diphenyl ethene with 2-(2-cyano-1-oxoethyl)-5-methylfuran which yielded 2-cyano -3,4-diphenylbutanolide without any cyclic peroxides. The oxidation of benzoylacetonitrile itself at 23 degrees C under an air atmosphere in the absence of alkene gave benzoic acid. Easy conversion of the 1,2-d ioxanes to furans was demonstrated, and mechanisms for the formation o f dihydrofurans and dioxanes as well as the unusual transformation to butanedione and butanolide were also discussed.