A solvent-free Jacobs-Gould reaction

The Jacobs-Gould intramolecular cyclisation of diethyl N-(6-methyl-2-pyridy l)aminomethylenemalonate (1) to 3-ethoxycarbonyl-7-methyl-1,8-naphthyrid-4- one (2) was conducted without solvent. Empirical kinetic data were extrapol ated to determine optimal reaction conditions. In contrast with established methods employing heat transfer oils, the reaction proceeded in high conve rsion, rapidly, predictably and controllably, at temperatures near 400 degr ees C. Since dilution was unnecessary, the procedure facilitated high throu ghput, was energy efficient, low polluting and offered convenient work-up. A continuous Jacobs-Gould reaction (of 1 to 2) was demonstrated for the fir st time.