Producing Dihydrofurans Using Palladium (II) Catalyst and Optimized Base

Dihydrofurans serve as building blocks for other compounds in organic synthesis. The main goal of this project was to discover an efficient and relatively inexpensive pathway for producing monosubstituted dihydrofurans in high yield from cyclic boronic half acids. Aldehydes were converted to homoallylic alcohols by the addition of allylmagnesium bromide. The alcohols were then transformed into cyclic boronic half acids using ringclosing metathesis with Grubbs 1st Generation Catalyst and alkenyl boronic esters. Finally, monosubstituted dihydrofurans were produced using a palladium (II) catalyst with a base. Palladium (II) catalysts that were tested include [1,1\u27- bis(diphenylphosphino)ferrocene]palladium (II) dichloride, palladium (II) acetate with and without triphenylphosphine, palladium (II) chloride with and without triphenylphosphine, and bis(triphenylphosphine)palladium(II) dichloride. The effect of an alkyl halide on dihydrofuran yield due to Suzuki-Miyaura coupling side product formation was also observed using 1-bromo-3-phenylpropane. Due to time constraints potassium carbonate was the only base that was tested. The results indicate that dihydrofuran production is possible with various palladium (II) catalysts using potassium carbonate as a base. Palladium (II) acetate with the addition of triphenylphosphine appears to form dihydrofuran in the highest yield