SYNTHESIS AND REACTIONS OF 2,3-DIMETHYLFURO[3,2-C]PYRIDINES

A number of substituted 2,3-dimethylfuro[3,2-c]pyridines was synthesiz ed. 3-(4,5-Dimethyl-2-furyl)propenoic acid (1) was converted to the ac id azide 2, which in turn was cyclized to give 2,3-dimethyl-5H-furo [3 ,2-c]pyridine-4-one (3) by heating at 240 degrees C in Dowtherm. The p yridone 3 was chlorinated with phosphorus oxychloride to give 4, which was reduced with zinc and acetic acid to 2,3-dimethylfuro[3,2-c]pyrid ine (5). Treatment of 4 with several secondary heterocyclic amines led to compounds 6a-6c. Reaction of pyridone 3 with phosphorus pentasulfi de rendered the thione 7, which was methylated to 8a. The 4-methoxy de rivative 8b was obtained from 4 with sodium methoxide. 2,3,5-Trimethyl furo[3,2-c]pyridine-4-ones (9) was obtained by reaction of 3 with meth yl iodide.