Sustainable Synthesis of 4-acylpyridines through air oxidation of dearomatized 4-alkylpyridines

Nitrogen containing heterocycles such as pyridines are a frequently encountered motif found in small molecule drugs approved by the FDA. Due to their prevalence in the pharmaceutical industry, green and effective synthetic routes towards these molecules are appealing. We detail a novel synthetic route towards 4-acypyridines via the ambient oxidation of alkylidene dihydropyridines (ADHPs). We then establish the robust and chemoselective nature of this oxidation by exploring substrates with various functional groups and multiple pyridylic sites. Finally, a series of time-course NMR studies reveal how to manipulate the stability of ADHPs by varying the nature of the chloroformate used to make these conjugated intermediates.