Water → N'-(2-chloro-phenyl)-N'-((1R,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester

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Reaction Conditions

Reaction Steps

Triethylamine (43 mL, 309 mmol) was added over 2-3 min to a cooled (0° C.) solution of (1R,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl chloride (Intermediate 20; 23.2 g, 103.8 mmol) in dry dichloromethane (260 mL), yielding a heavy precipitate. Dichloromethane (25 mL) was added, followed by N′-(2-chloro-phenyl)-hydrazinecarboxylic acid tert-butyl ester (Intermediate 30; 19.36 g, 79.8 mmol) in one portion. Dichloromethane (35 mL) was added and the mixture was stirred at 0° C. for 5 min and then heated in an oil bath at 50° C. for 4 h. The mixture was poured into cold water (500 mL) and the layers were separated. The aqueous layer was extracted with dichloromethane (2×300 mL) and the combined organic layers were washed with brine (200 mL), dried (magnesium sulfate), filtered, evaporated, and purified by silica gel chromatography, eluting with 20-100% ethyl acetate/petroleum ether. Fractions homogeneous for the product were evaporated and dried under high vacuum to give N′-(2-chloro-phenyl)-N′-((1R,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (23.4 g, 70%) as a pale foam.

Provenance & Evidence