Potassium Carbonate → 4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-(but-2-enyloxymethyl)-4-iodo-2-methoxy-pyridine (228 g, 0.714 mol), potassium carbonate (200 g, 1.45 mol) and tetrabutylammonium chloride (100 g, 0.36 mol) in N,N-dimethylformamide (3.5 L) is purged with nitrogen for 20 min prior to the addition of palladium(II) acetate (3.75 g, 0.0167 mol) and tris(triphenylphosphine) rhodium(I) chloride (5.31 g, 0.00574 mol). The mixture is heated at 90° C. for about 4 h, cooled to below 50° C. and filtered through a pad of Celite®. The pad is washed with tert-butyl methyl ether (200 ml). The filtrate is washed with water (4×3 L), dried over sodium sulfate (260 g) and concentrated to a dark oil that is vacuum distilled (about 85°-98° C., about 6 mm Hg) to provide 4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine as a yellow-orange oil which contains a 14.3:1 ratio of 4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine to the corresponding double bond isomer, 4-ethylidene-8-methoxy-3,4-dihydro-1H-pyrano[3,4-c]pyridine.

Provenance & Evidence