(4-Chlorophenyl)hydrazine → 2-(4-chlorophenyl)-1,4-dihydro[1]benzothiopyrano[4,3-c]pyrazol-3(2H)-one

Participants

Reaction Conditions

Reaction Steps

4Oxo-3-thiochromancarboxylic acid methyl ester (10.4 g., 0.047 mole), [prepared by the method of Moriwake, J. Med. Chem. 9, 163 (1966)], was added to a round bottom flask containing p-chlorophenylhydrazine (7.4 g., 0.052 mole) and 3 ml. of glacial acetic acid. After stirring to obtain a homogeneous mixture, the reaction mixture was heated under nitrogen at an oil bath temperature of 115° C. The reaction mixture quickly liquefied and then turned to a yellow solid. Heating was continued at 115° C. for 20 minutes and the temperature then gradually raised to 180° C. and maintained there for about an hour. The reaction mixture was then cooled to room temperature, the solid was collected by filtration, washed with ether and dried. Recrystallization from isopropanol afforded product, m.p. 235° to 237° C. Weight: 10.3 g (70%).

Provenance & Evidence