Efficient synthesis of (S)-(+)-lycoperdic acid has been achieved by use of the stereoselective hydroxylation of the enolate derived from the bicyclic lactam 3 with the molybdenum oxidizing reagent, MoOPH (MoO5·Py·HMPA, oxodiperoxymolybdenum(pyridine)(hexamethylphosphoric triamide)), as a key step.