Diethyl Ether → methyl 2-[4-(3,4-dihydro-2H-1-benzopyran-6-yl)-2,5-dimethylthiophen-3-yl]-2-oxoacetate

Participants

Reaction Steps

A solution of 2-[4-(3,4-dihydro-2H-1-benzopyran-6-yl)-2,5-dimethylthiophen-3-yl]-2-oxoacetic acid (42a) (1.09 g, 3.43 mmol) in methanol (10 mL) was cooled to 0° C. Trimethylsilyldiazomethane 2N in diethyl ether (6.89 mL, 13.7 mmol) was added dropwise and the reaction mixture was stirred at room temperature for 3 hours. The precipitate was filtered off and washed with cooled methanol (5 mL). The filtrate was concentrated in vacuo and the residue was dissolved in a minimum of methanol. The solution was sonicated for a few seconds and the precipitate was filtered and washed with cooled methanol. The precipitates were combined to provide the desired ester (42b) (820 mg, 2.48 mmol, 72% over two steps) as a beige solid, which was used without further purification.

Provenance & Evidence