Synthesis of AC Ring Analogs. Established methods for synthesizing the AC ring of colchicine are almost exclusively related to the natural product total synthesis, 20 and are not easily adaptable to analogs without a B ring. The only established AC ring strategy that seemed viable for the synthesis of 6 was an 11-step synthesis of a chloro-AC analog reported over 30 years ago by Banwell. 12a Thus, a new synthetic strategy was pursued. We became specifically interested in the potential of coupling the intermolecular 3-hydroxy-4-pyrone-based oxidopyrylium cycloaddition reaction 21 with a reductive ring-opening, which would rapidly generate the AC ring in only two steps. Studies from our lab have revealed that oxidopyrylium dimer 15 can be made on multi-gram scale without any chromatography, 22