(2R,4'R,8a'R)-1-tert-butyl 4'-methyl 6'-oxohexahydrospiro[pyrrolidine-2,7'-pyrrolo[2,1-b][1,3]thiazine]-1,4'-dicarboxylate

(2R,4'R,8a'R)-1-tert-butyl 4'-methyl 6'-oxohexahydrospiro[pyrrolidine-2,7'-pyrrolo[2,1-b][1,3]thiazine]-1,4'-dicarboxylate