The synthesis of new 7-azabicyclo[2.2.1]heptane derivatives has been achieved in a four-step synthetic sequence, starting from readily available cyclohex-3-enecarboxylic acid, Curtius reaction, stereoselective bromination leading to major benzyl(cis-3,trans-4-dibromocyclohex-1yl)carbamates (amides or sulfonamides), followed by NaH-mediated intramolecular cyclization. The synthesis and free radical cyclization of precursors 4-7, as well as the synthesis of a conformationally constrained epibatidine analogue 3 exploiting the reactivity of the 7azabicyclo[2.2.1]hept-2-yl radical in intramolecular reactions, are described. The N-sulfonyl functional motif is the only one to afford a cyclized product when incorporated in the radical precursor.

中文翻译：

---

新型7-氮杂双环[2.2.1]庚烷衍生物的合成

新的 7-氮杂双环 [2.2.1] 庚烷衍生物的合成分四步合成，从容易获得的环己-3-烯羧酸开始，Curtius 反应，立体选择性溴化导致主要的苄基 (cis-3, trans-4-dibromocyclohex-1yl)carbamates（酰胺或磺酰胺），然后是 NaH 介导的分子内环化。描述了前体 4-7 的合成和自由基环化，以及利用 7azabicyclo[2.2.1]hept-2-yl 自由基在分子内反应中的反应性合成受构象限制的 epibatidine 类似物 3。当结合到自由基前体中时，N-磺酰基功能基序是唯一提供环化产物的基序。