Synthesis of benzodioxepanes

Four benzodioxepanes 1a–1d were prepared from reaction of 4-methoxy-3-hydroxybenzaldehyde 4 via a series of reasonable transformations, including the regioselective PhBCl2-mediated double allylation of 4, one-pot combination of ring-closing metathesis of skeleton 3 and Baeyer–Villiger reaction, O-allylation of skeleton 2, Claisen rearrangement of skeleton 5, and one-pot combination of ring-closing metathesis and hydrogenation.