反应详情

温度

0 °C

Oxalyl chloride (2 M in dichloromethane; 35.1 mL, 70.3 mmol) and dimethylformamide (a few drops) were added to a solution of (1S,4S)-3-camphorcarboxylic acid (Intermediate 24; 6.00 g, 30.6 mmol) in dichloromethane (31 mL) at 0° C. The reaction mixture was stirred at 0° C. for 30 min and then at room temperature overnight. The solvent was evaporated, and the residue was co-evaporated three times with dichloromethane and then dried under high vacuum to give crude (1S,4S)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl chloride. The crude acid chloride was dissolved a minimal amount of dichloromethane and added over a period of 20 min to a cooled (˜0° C.) solution of N-benzyl-hydrazinecarboxylic acid tert-butyl ester (Intermediate 27; 7.47 g, 33.6 mmol) in a mixture of dichloromethane (93 mL) and saturated aqueous sodium hydrogen carbonate (47 mL). The reaction mixture was stirred at 0° C. for 30 min, at room temperature for 3 h, and then at about 50° C. overnight. The reaction mixture was cooled and the layers were separated. The aqueous layer was extracted with dichloromethane (2×100 mL) and the combined organic layers were dried (sodium sulfate), filtered and evaporated to give crude N-benzyl-N′-((1S,4S)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester which was used directly in the next step.

1. customat room temperature
2. customovernight
3. customThe solvent was evaporated
4. customdried under high vacuum