Methyl 5-bromothiophene-2-carboxylate → 5-(3-tert-Butoxycarbonylamino-prop-1-ynyl)-thiophene-2-carboxylic Acid Methyl Ester

Participants

Reaction Steps

A mixture of prop-2-ynyl-carbamic acid tert-butyl ester (from Preparation 41, 1.67 mmol, 0.011 mmol), 5-bromo-thiophene-2-carboxylic acid methyl ester (2.50 g, 0.011 mmol), tetrakistriphenylpyosphine(O) palladium (0.622 g, 0.0538 mmol), Cul (0.102 g, 0.538 mmol) and triethylamine (1.57 mL, 0.011 mmol) in 50 mL acetronitrile was heated at reflux for 16 h. The reaction was cooled to room temperature, diluted with 75 mL EtOAc, washed with 5.5% HCl, water and brine, dried over MgSO4, filtered and concentrated in vacuo to an oil. The product was purified via flash chromatography (9:1 to 4:1 hexanes:EtOAc) to afford the title compound of Step A as an oil (2.06 g). MS 313 (M+18).

Provenance & Evidence