Aza-[4 + 2] annulation reactions between α-vinyl Morita–Baylis–Hillman (MBH) adducts and cyclic imines have been developed, achieving regiodivergent synthesis of two distinct types of azatricyclic products. The process initiates with an S_N2′′ addition of triphenylphosphine to the MBH adducts, forming a pentadienyl phosphonium intermediate. This intermediate then undergoes aza-[4 + 2] annulation with saccharin-derived ketimines to yield sultam-fused tetrahydropyridines with exomethylene groups in moderate to good yields. Alternatively, employing DABCO and trifluoroacetic acid facilitates an aza-[4 + 2] annulation with 3,4-dihydroisoquinoline, resulting in the formation of exomethylene-bearing benzoquinolizidines with reversed orientational regioselectivity.

中文翻译：

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α-乙烯基 Morita-Baylis-Hillman 加合物的 Aza-[4 + 2] 环化用于区域差异合成带有外亚甲基的氮杂三环化合物

α-乙烯基 Morita-Baylis-Hillman (MBH) 加合物和环状亚胺之间的 Aza-[4 + 2] 成环反应已被开发出来，实现了两种不同类型氮杂三环产物的区域差异合成。该过程以三苯基膦 S _N 2'' 加成到 MBH 加合物开始，形成戊二烯基鏻中间体。然后，该中间体与糖精衍生的酮亚胺进行氮杂-[4 + 2]环化，以中等至良好的产率产生具有外亚甲基的磺内酰胺稠合四氢吡啶。或者，使用 DABCO 和三氟乙酸促进氮杂-[4 + 2] 与 3,4-二氢异喹啉成环，从而形成具有反向区域选择性的带有外亚甲基的苯并喹啉齐啶。