SYNTHETIC STUDIES ON BICYCLOMYCIN. I. SYNTHESIS OF 1-ALLYL AND BENZOYL-8,10-DIMETHYL-6-METHOXY-5-METHYLENE-8,10-DIAZA-2-OXABICYCLO(4.2.2)DECANE-7,9-DIONE, WHICH HAVE THE BICYCLO RING SYSTEM FOUND IN ANTIBIOTIC BICYCLOMYCIN