One-Pot Synthesis of Functionalized 2,5-Dihydrofurans via an Amine-Promoted Petasis Borono–Mannich Reaction

A series of functionalized 2,5-dihydrofurans were efficiently synthesized
via an amine-promoted Petasis borono–Mannich reaction of 4-substituted
1,2-oxaborol-2(5H)-ols with salicylaldehydes in high
yields. The process, which combines a boronic acid-based Mannich reaction
and a highly efficient intramolecular SN2 cyclization,
provides a one-step and efficient route toward 2,5-dihydrofurans from
simple and stable starting materials.