5-methoxy-3-[((S)-1-methoxycarbonyl-3-methyl-butylamino)-methyl]-2H-chromene-2-carboxylic acid ethyl ester → (S)-2-(8-methoxy-3-oxo-3,3a-dihydro-1H-chromeno[2,3-c]pyrrol-2-yl)-4-methyl-pentanoic acid methyl ester

Participants

Reaction Steps

A solution of 5-methoxy-3-[((S)-1-methoxycarbonyl-3-methyl-butylamino)-methyl]-2H-chromene-2-carboxylic acid ethyl ester (0.45 g, 1.14 mmol) and N,N′-diisopropylethyl amine (0.8 mL, 4.50 mmol) in acetonitrile (2 mL) was heated in a sealed tube at 140° C. for 48 hours. The reaction mixture, after aqueous work-up, extracted with ethyl acetate (3×). The combined ethyl acetate layer was washed with brine, and dried over anhydrous sodium sulfate. The organic layer was concentrated in vacuo and the residue was purified over neutral alumina using hexanes-ethyl acetate as eluents to afford (S)-2-(8-methoxy-3-oxo-3,3a-dihydro-1H-chromeno[2,3-c]pyrrol-2-yl)-4-methyl-pentanoic acid methyl ester (0.25 g, 62.9%) as a solid.

Provenance & Evidence