New Efficient Approaches to Functionalized 2-Substituted Furopyridines

2-Ethynyl-3-pyridinols and 3-ethynyl-2-pyridinols, readily available from halopyridinols, have been treated with aryl/heteroaryl halides or vinyl triflates to give 2-substituted furo[3,2-b]pyridines and 2-substituted furo[2,3-b]pyridines through a coupling/cyclization process. Two catalyst systems have been used: PdCl2(PPh3)2-CuI and Pd2(dba)3-P(t-Bu)3. Halopyridinols have been employed for an alternative approach to 2-substituted furo[2,3-b]pyridines and 2-substituted furo[2,3-c]pyridines via 2-(trimethylsilyl)furopyridines, 2-iodofuropyridines, palladiumcatalyzed reactions.