(2-bromo-4-chlorophenyl)hydrazine

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A stirred solution of (2-bromo-4-chloro-phenyl)-hydrazine (step A) (1.98 g, 8.94 mmol) in ethanol (6.5 ml) was cooled to 0° C. and a solution of commercially available methyl 2-ketobutyrate (1.08 g, 1.04 ml, 9.3 mmol) in ethanol (2 ml) was added drop wise at 0° C. for 15 min. After the mixture was allowed to stir at room temperature for 3 h it was evaporated. The crude material (3.01 g) was purified by flash chromatography on silica gel (heptane/ethyl acetate 0-20%) to yield (Z)-2-[(2-bromo-4-chloro-phenyl)-hydrazono]-butyric acid methyl ester (2.67 g, 94%) as a light yellow solid, MS (ISP) m/z=321.3 [(M+H)+], mp 67° C. was evaporated The crude material (3.01 g) was purified by flash chromatography on silica gel (heptane/ethyl acetate 0-20%)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A stirred solution of (2-bromo-4-chloro-phenyl)-hydrazine (step A) (1.98 g, 8.94 mmol) in ethanol (6.5 ml) was cooled to 0° C. and a solution of commercially available methyl 2-ketobutyrate (1.08 g, 1.04 ml, 9.3 mmol) in ethanol (2 ml) was added drop wise at 0° C. for 15 min. After the mixture was allowed to stir at room temperature for 3 h it was evaporated. The crude material (3.01 g) was purified by flash chromatography on silica gel (heptane/ethyl acetate 0-20%) to yield (Z)-2-[(2-bromo-4-chloro-phenyl)-hydrazono]-butyric acid methyl ester (2.67 g, 94%) as a light yellow solid, MS (ISP) m/z=321.3 [(M+H)+], mp 67° C. was evaporated The crude material (3.01 g) was purified by flash chromatography on silica gel (heptane/ethyl acetate 0-20%)