Scheme 3: a, Ac2O, pyridine, dimethylaminopyridine (DMAP); b, 3,5 dimethylpyrazole, CrO3, CH2Cl2, −15 C; c, Pd/C, H2, EtOAc; d, L-selectride, THF, −78 C; e, Burgess reagent, benezene, reflux; f, KOH, MeOH; g, PCC, NaOAc; h, NaCIO2, NaH2PO4, 2-methyl-2-butene.