Synthesis of Polysubstituted Pyridines and Pyrazines via Truce-Smiles Rearrangement of Amino Acid-Based 4-Nitrobenzenesulfonamides.

Immobilized l-glutamic acid ß-methyl ester was sulfonylated with 4-nitrobenzenesulfonyl chloride and alkylated with various α-haloketones. The resulting sulfonamides were reacted with potassium trimethylsilanolate. Then, upon cleavage from the polymer support, tetrasubstituted pyridines were produced as the result of one-step C-arylation, aldol condensation, and oxidation. When cleavage from the resin occurred before the trimethylsilanolate treatment, C-arylation was followed by enamination, which yielded trisubstituted pyrazines. Through the developed protocols, targeted synthesis of novel heterocyclic derivatives was performed using mild reaction conditions and a number of readily available starting materials.