Triethylamine → (E)-ethyl 3-(1-(4-fluorophenyl)-6-methyl-1H-indazol-5-yl)acrylate

Participants

Reaction Conditions

Reaction Steps

(a)(b) 1-(4-Fluorophenyl)-6-methyl-1H-indazol-5-ol [(484 mg, 2.0 mmol; prepared as described in Example 105(c)] was dissolved in DCM (20 mL) and pyridine was added (0.16 mL, 2 mmol) followed by triflic anhydride (0.36 mL, 2.1 mmol). After 1 h, the reaction was washed with 1 M HCl and the aqueous layer was dried over MgSO4, filtered, and concentrated. The crude 1-(4-fluorophenyl)-6-methyl-1H-indazol-5-yltrifluoromethanesulfonate was taken up in 20 mL DMF, transferred to a stainless steel pressure bomb, and treated with ethyl acrylate (200 mg, 2 mmol), triethylamine (0.28 mL, 2 mmol), and Pd(PPh3)2Cl2 (160 mg, 0.2 mmol) and heated at 110° C. for 6 h. The reaction was incomplete so additional ethyl acrylate (200 mg, 2 mmol) and Pd(PPh3)2Cl2 (160 mg, 0.2 mmol) was added and the reaction was sealed and heated for 16 h. The reaction was cooled, diluted with EtOAc, washed with brine, and the organic phase was dried over MgSO4, filtered, and concentrated. The residue was purified by MPLC using SiO2 and a 1:9 EtOAc/hexane to 1:1 gradient. Obtained 350 mg (54% yield, 2 steps) of (E)-ethyl 3-(1-(4-fluorophenyl)-6-methyl-1H-indazol-5-yl)acrylate. MS found: (M+H)+=325.

Provenance & Evidence