1: 89.1 percent / trifluoroacetic anhydride 2: 1.) mercuric acetate; 2.) sodium borohydride / 1.) water, THF, r.t. 4: 1.) ozon; 2.) dimethyl sulfide / 1.) ethyl acetate, -70 deg C 6: H2O / hydrolysis 7: aluminium chloride / C2H5SH View Scheme