Photo-on-Demand Synthesis of Vilsmeier Reagents with Chloroform and Their Applications to One-Pot Organic Syntheses.

The Vilsmeier reagent (VR), first reported a century ago, is a versatile reagent in a variety of organic reactions. It is used extensively in formylation reactions. However, the synthesis of VR generally requires highly toxic and corrosive reagents such as POCl, SOCl, or COCl. In this study, we found that VR is readily obtained from a CHCl solution containing ,-dimethylformamide or ,-dimethylacetamide upon photo-irradiation under O bubbling. The corresponding Vilsmeier reagents were obtained in high yields with the generation of gaseous HCl and CO as byproducts to allow their isolations as crystalline solid products amenable to analysis by X-ray crystallography. With the advantage of using CHCl, which bifunctionally serves as a reactant and a solvent, this photo-on-demand VR synthesis is available for one-pot syntheses of aldehydes, acid chlorides, formates, ketones, esters, and amides.