We report a novel enantioselective and regioselective [2 + 2] cycloaddition of allenoate and ,-cyclic ketimine catalyzed by a quinidine derivative. The methodology enables the synthesis of fused tricyclic azetidines with a quaternary stereogenic center exhibiting high enantioselectivities. The broad range of substrates demonstrates the generality of the protocol, and the resulting functional products can be easily converted to a variety of valuable synthons. To elucidate the plausible reaction mechanism and how the catalyst affects absolute stereocontrol over the products, we conducted the corresponding density functional theory (DFT) calculations.
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