Acetic Acid → Ethyl 4,5-dihydro-5-methyl-4-oxo-imidazo(1,5-a)pyrido(2,3-e)pyrazine-3-carboxylate

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Reaction Steps

To a stirred solution of 1,2,3,4-tetrahydro-4-methyl-2,3-dioxo-pyrido(2,3-b)-pyrazine (5g) in 50 ml of dry dimethyl formamide (DMF) was added potassium-t-butylate (4 g). The mixture was allowed to stir at room temperature for 15 min whereafter it was cooled to -25° C. and charged with diethyl chlorophosphate (5ml). Stirring continued at 0° C. for 15 min, then it was cooled to -20° C. whereafter a preformed -30° C. cold solution of ethyl isocyanoacetate (3.9ml) and pottasium-t-butylate (4 g) in 30ml of dry DMF was added. The resulting solution was allowed to obtain room temperature before acetic acid was added (1,5 ml). The DMF was removed by evaporation in vacuo, whereafter the residue was treated with water to give the crude title compound as pale crystals. Recryst in 96% ETOH M.p. 233°-234° C.

Provenance & Evidence