8-Allyl-1-ethyl-7-fluoro-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid methyl ester → 8-Allyl-1-ethyl-7-fluoro-4-oxo-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid methyl ester

Participants

Reaction Steps

A solution of the ester (0.21 g, 0.63 mmol, prepared as described in Step A), in 10 ml of CH3CN--H2O(9:1, v/v) was added dropwise to a stirred solution of TEMPO-BF4 in 10 ml CH3CN--H2O (9:1, v/v). Stirring was continued for 2 h and the reaction mixture was concentrated in vacuo. The residue was partitioned between Et2O and H2O. The organic phase was washed with brine and dried (Na2 SO4). Removal of solvent provides a yellow oil which was purified by flash chromatography (silica gel, hexane-EtOAc 2:1) to give 0.18 g of product as an off white solid.

Provenance & Evidence