反应详情

Starting material (10(c)) was prepared as follows. Pyridine 2,5-dicarboxylic acid 2-methyl ester (10(a)) (9.0 g; 0.05 mole) was added to stirring thionyl chloride (25 mL) and the mixture refluxed gently for 2.5 hours. The excess thionyl chloride was removed in vacuo and the residual solid azeotroped with toluene (2×25 mL) to give 5-chlorocarbonyl-pyridine-2-carboxylic acid methyl ester (10(b)) which was used crude in the next reaction.

1. customwas prepared
2. temperaturethe mixture refluxed gently for 2.5 hours
3. customThe excess thionyl chloride was removed in vacuo
4. customthe residual solid azeotroped with toluene (2×25 mL)