Progress in the photocatalysed synthesis of pyridines

A new and highly selective methodology for the construction of a large vari ety of mono- and polysubstituted pyridines is described. The synthesis is e fficient under irradiation employing artificial light as well as with the s un as light source. In particular the latter method allows the preparation of substituted pyridines under mild conditions and affords the possiblity t o scale up the reaction. Deduced from our mechanistic investigations condit ions for an efficient control of the selectivity could be identified includ ing the reaction in water as reaction medium. The new method is also useful for the synthesis of pyridines with central or axial chirality and require s therefore ongoing attention.