ω-Alkynal ester 3, prepared from (S)-propylene oxide 4, yields the macrocyclic (6R)-allylic alcohol 2 (60% yield, 83% d.e.) in one operation via monohydroboration, boron/zinc-transmetalation and (−)-DAIB “catalyzed” intramolecular alkenylzinc/aldehyde addition. Introduction of the C(2)–C(3) double bond by selenoxide elimination (2 → 8), hydroxy-directed epoxidation (8 → 9), acetate assisted α-epoxide opening (10 → 12) and acidic methanolysis provides pure (+)-aspicilin (1) in 22% overall yield from 4.