Lewis-Base-Catalyzed [1 + 2 + 2] Annulation Reaction of Morita–Baylis–Hillman Carbonates with Unsaturated Pyrazolones: Construction of All-Stereogenic Carbon Cyclopentane-Fused Dispiropyrazolones

The first Lewis-base-catalyzed unexpected [1 + 2 + 2] annulation reaction between Morita–Baylis–Hillman carbonates and unsaturated pyrazolones was developed. The multicyclic cyclopentane-fused dispiropyrazolone constructions containing five contiguous stereogenic centers, including two spiro quaternary centers, were prepared with excellent yields (81–98%) and moderate to good diastereoselectivities (1:1 to 13:1). Further transformation and gram-scale operations were also achieved efficiently.

首例路易斯碱（Lewis base）催化的莫里塔-贝利斯-希尔曼碳酸酯（Morita–Baylis–Hillman carbonates）与不饱和吡唑啉酮（unsaturated pyrazolones）间的意外[1+2+2]环合反应被成功开发。利用该反应可制备含有五个连续手性中心（包含两个螺环季碳中心）的多环环戊烷并二螺吡唑啉酮骨架，产物收率优异（81%~98%），非对映选择性中等至良好（1:1至13:1）。此外，该反应还可高效完成后续衍生转化以及克级规模放大操作。