Preparation of highly functionalized pyridylmagnesium reagents for the synthesis of polyfunctional pyridines

Functionalized iodopyridines bearing either a chloride, ester or nitrile fu nction were converted to the corresponding organomagnesium derivatives at - 40 degrees C or -78 degrees C by treatment with i-PrMgBr (1.1 equiv, 0.5 h, > 90% yield). The resulting functionalized Grignard reagents react with al dehydes, TosCN directly or with allylic bromides and benzoyl chloride after transmetalation with CuCN leading to polyfunctional pyridines.