Pyridine → Methyl 1,4,5,7-tetrahydro-2-methyl-4-(2-methylphenyl)-5-oxofuro[3,4-b]pyridine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

In an operation carried out in a manner similar to that described in the preceding example, 1.52 grams of 80 percent pyridinium bromide perbromide (3.81 millimoles) was added in one portion to a solution of 1.00 gram (3.17 millimoles) of dimethyl 2,6-dimethyl-4-(o-tolyl)-1,4-dihydropyridine-3,5-dicarboxylate and 0.40 milliliter of pyridine in 20 milliliters of dry chloroform cooled to 0° C. The mixture was stirred for 30 minutes at 0° C., then at reflux temperature for 1.5 hours. Thereafter, the mixture was cooled, washed successively with hydrochloric acid and brine, dried, subjected to reduced pressure to remove the solvent and to obtain as residue crude methyl 2-methyl-4-(o-tolyl)-5-oxo-1,4,5,7-tetrahydrofuro[3,4-b]pyridine-3-carboxylate product. The crude product was chromatographed on silica and eluted with 65 percent ethyl acetate--35 percent hexane to obtain 0.58 gram (61 percent yield) of white crystalline material which after recrystallizing from ethyl acetate-hexane and drying at 80° C./0.005 mm Hg for 17 hours had a melting point of 224°-225° C. and the following analyses:

Provenance & Evidence