Successive regioselective metalations of fused heterocycles: synthesis of polyfunctionalized furo[3,2-b]pyridines.

The furopyridine framework was chosen as a target for a lithiation study, in order to define the most effective conditions leading to the total functionalization of the heterocycle. Consequently, a detailed procedure for successive regioselective lithiations/electrophilic trapping of furo[3,2-b]pyridines is described and afforded several polyfunctionalized derivatives in good overall yields. A Pd-catalyzed cross-coupling reaction is also described and easily yielded the 7,7'-bifuro[3,2-b]pyridine.