Oxalyl chloride → HCID 57941380, compound

Participants

Reaction Conditions

Reaction Steps

Oxalyl chloride (4.1 mL, 46.9 mmol) was added dropwise to a solution of (1S,4S)-3-camphorcarboxylic acid (Intermediate 24; 4.0 g, 20.4 mmol) and N,N-dimethylformamide (3 drops) in dichloromethane (20 mL) at 0° C. The reaction mixture was stirred at 0° C. for 20 min and then at room temperature for 1.5 h. 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 as an orange-brown oil. The crude acid chloride was dissolved in dichloromethane (52 mL) at 0° C., and triethylamine (6.5 mL, 46.8 mmol) and N-methyl-hydrazinecarboxylic acid tert-butyl ester (Intermediate 1; 2.29 g, 15.7 mmol) were added. The reaction mixture was stirred at 0° C. for 15 min and then at ˜50° C. for 2 h. The reaction mixture was cooled and partitioned between dichloromethane and water. The aqueous layer was extracted twice with dichloromethane and the combined organic layers were dried (sodium sulfate), filtered and evaporated to give crude N-methyl-N′-((1S,4S)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (6.15 g, 93%) which was used directly in the next step.

Provenance & Evidence