Synthesis of fused-pyran derivatives

We introduce, for the first time, an inorganic base-mediated cyclization and auto-oxidation of bisallenones/bisalkynones. This reaction is realized under mild conditions through precise control of the base and atmosphere, providing a wide range of structurally diverse fused-pyran derivatives with moderate to excellent yields. Utilizing KOH as the initiator under a nitrogen atmosphere, a series of novel cyclohexane-fused pyran derivatives was obtained as the primary product. In contrast, under aerobic conditions with Na