Hydrochloric Acid → HCID 16116997, compound

Participants

Reaction Steps

Triethylamine (440 μL, 3.2 mmol) was added to solution of (1S,4S)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl chloride (Intermediate 25; 329 mg, 1.5 mmol) in 1,2-dichloroethane (4 mL) over 1 min. Then a solution of N′-(2,5-dichloro-phenyl)-N-methyl-hydrazinecarboxylic acid tert-butyl ester (300 mg, 1.03 mmol) in 1,2-dichloroethane (8 mL) was added over 2 min. The reaction mixture was stirred at room temperature for 15 min and then heated in an oil bath at 50° C. for 30 min. An additional portion of N′-(2,5-dichloro-phenyl)-N-methyl-hydrazinecarboxylic acid tert-butyl ester (290 mg, 1.0 mmol) in 1,2-dichloroethane (4 mL) was added and the mixture was heated in an oil bath at 50° C. for 1.5 h. A solution of HCl in dioxane (4 M; 8 mL, 32 mmol) was added and the mixture was heated in an oil-bath at 100° C. for 1 h. The reaction mixture was allowed to cool, silica gel was added, the solvent was evaporated and the mixture was purified using an ISCO 40 g column, eluting with 60-100% ethyl acetate/hexanes. Fractions homogeneous for the product were evaporated, co-evaporated successively with methanol and diethyl ether, and then dried under high vacuum at 95° C. to give (4R,7S)-2-(2,5-dichloro-phenyl)-1,7,8,8-tetramethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (24 mg, 37%) as a pale yellow solid. ES(+)-MS (M+H) 351.

Provenance & Evidence