反应详情

To a stirring solution of tert-butyl (2S,4EZ)-2-(hydrazinocarbonyl)-4-(methoxyimino)-1-pyrrolidinecarboxylate (Intermediate 9, 1.84 mmoles; 500 mg) and triethylamine (2.76 mmoles; 27 mg) in THF (25 mL) at 0° C. was added 1,1′-carbonyldiimidazole (2.76 mmoles, 448 mg). The stirring was continued for 5 hours. Another portion of triethylamine and 1,1′-carbonyldiimidazole were added and stirring was continued at room temperature overnight. The solvent was evaporated and the residue was dissolved in EtOAc and washed with NH4Clsat., and 10% NaHCO3, and brine. The organic layer was dried over Na2SO4 and evaporated to dryness to give the desired N-protected intermediate, tert-butyl (2S,4E)-4-(methoxyimino)-2-(5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)-1-pyrrolidinecarboxylate, as a white foam (460 mg, 84%).

1. waitwas continued at room temperature overnight
2. customThe solvent was evaporated
3. dissolutionthe residue was dissolved in EtOAc
4. washwashed with NH4Clsat
5. dry with materialThe organic layer was dried over Na2SO4
6. customevaporated to dryness