烯烃可以通过(32)环加成和随后的1,3-偶极子的环回来裂解,典型的臭氧(O3),但叠氮化物(R-N3)变体很少见。这些叠氮化物向烯烃重氮基转移(DGT)的化学选择性通常是不利的,从而限制了它们的合成效用。在这里,这项工作公开了钯催化的分子内叠氮化物合成烯烃DGT,赋予竞争氮丙啶的化学选择性。数据支持与其他已知的金属催化的叠氮化物/烯烃反应不同的催化环回机理:硝基/金属基团和(32)环加成。动力学实验揭示了一种不寻常的机理,其中催化剂在速率控制步骤中不起作用。更确切地说,它在产品确定步骤期间是活跃的。催化DGT用于合成N-杂环喹唑啉酮,与医学相关的结构核心。我们还报告了竞争性氮丙啶和随后的环扩展到另一个感兴趣的N-杂环核心结构,苯二氮卓酮类。
Alkenes can be cleaved by means of the (3+2) cycloaddition and subsequent cycloreversion of 1,3-dipoles, classically ozone (O3 ), but the azide (R-N3 ) variant is rare. Chemoselectivity for these azide to alkene diazo group transfers (DGT) is typically disfavored, thus limiting their synthetic utility. Herein, this work discloses a palladium-catalyzed intramolecular azide to alkene DGT, which grants chemoselectivity over competing aziridination. The data support a catalytic cycloreversion mechanism distinct from other known metal-catalyzed azide/alkene reactions: nitrenoid/metalloradical and (3+2) cycloadditions. Kinetics experiments reveal an unusual mechanistic profile in which the catalyst is not operative during the rate-controlling step, rather, it is active during the product-determining step. Catalytic DGT was used to synthesize N-heterocyclic quinazolinones, a medicinally relevant structural core. We also report on the competing aziridination and subsequent ring expansion to another N-heterocyclic core structure of interest, benzodiazepinones.