EP1966233A1 - AN OXIDATION PROCESS FOR THE PREPARATION OF N-[3-AMINO-1- (CYCLOBUTYLMETHYL)-2,3-DIOXOPROPYL-3-{N-[(TERT-BUTYLAMINO)CARBONYL]-3-METHYL-L-VALYL}-6,6-DIMETHYL-3-AZABICYCLO[3.1.0]HEXANE-2-CARBOXAMIDE AND RELATED COMPOUNDS