Dimethyl Succinate → 2-(7-methyl-1H-indazol-5-ylmethylene)-succinic acid 1-methyl ester

Participants

Reaction Conditions

Reaction Steps

To a mixture of 7-methyl indazole aldehyde (0.2619 g, 1.64 mmol) and DBE-4 dibasic ester (dimethyl succinate) (0.32 mL, 2.45 mmol) in t-butanol (20 mL) was added potassium t-butoxide (0.4036 g, 3.60 mmol). The reaction mixture was heated at 50° C. for 2 h under nitrogen. After a further 16 h at room temperature, the solvent was removed in vacuo and the residue was taken up in water (100 mL) and extracted with ethyl acetate (3×50 mL). The aqueous layer was acidified with 1 N hydrochloric acid to pH 3˜4 and extracted with ethyl acetate (3×50 mL). The combined ethyl acetate solution was dried and concentrated in vacuo to give the crude product as a yellow solid (99%, cis/trans isomer approximately 40:60). The crude mixture was carried to next step without further purification. Mass spec.: 275 (MH)+.

Provenance & Evidence