Metal-Free Solvent/Base-Switchable Divergent Synthesis of Multisubstituted Dihydrofurans.

A general protocol for the synthesis of multisubstituted 2,3-dihydrofuran-2-carbonitriles and 4,5-dihydrofuran-3-carbonitriles was demonstrated under a metal-free regime with the same oxidant, TBHP. By simply switching the reaction solvent and base, the reaction proceeds via two pathways. An unexpected -CN group migration rearrangement and hydroxylation have occurred in nonpolar and polar solvents, respectively, under the reported conditions. Furthermore, the source of the hydroxyl group and hydrogen in the reaction is indirectly confirmed with isotope labeling studies.