Acetic Acid → Ethyl 4,5,6,7-tetrahydro-1,3-dimethyl-4-oxo-1H-indazole-5-carboxylate

Participants

Reaction Steps

A suspension of sodium hydride (14.6 g, 0.365 mol, 60% oil dispersion) in dry benzene at 5° to 10° C. is treated with 1,5,6,7-tetrahydro-1,3-dimethyl-4H-indazole-4-one (30.0 g, 0.183 mol). The reaction mixture is treated dropwise with ethyl carbonate (45.0 mL, 0.365 mol) and ethanol (1.0 mL) with cooling, stirred for 11 hours at reflux temperature, cooled to room temperature and treated with acetic acid (24.1 g, 0.400 mol) and water. The phases are separated, the organic phase is set aside and the aqueous phase is extracted with ether. The organic phases are combined, washed with water, dried (Na2SO4) and concentrated in vacuo. The resultant residue is chased twice with toluene, recrystallized from (2:1) methylene chloride:heptane and a second time from 50% tetrahydrofuran:heptane to afford the title product (27.6 g, 63.9%), mp 76.5°-79° C.

Provenance & Evidence