An iodine-mediated hydration reaction of alkynes serves as a green alternative to metal-catalyzed procedures. Previous work has shown that this method works well with terminal alkynes on keto-functionalized scaffolds, including 1,3-dicarbonyls and their heteroatom analogues. It was hypothesized that the reaction proceeds through a 5-exo-dig neighboring group participation (NGP) cyclization and an α-iodo intermediate. The work described herein probes the existence of the intermediate through NMR investigations and explores the scope of the hydration process with internal alkynes. The NMR experiments confirm the existence of the α-iodo intermediate, and methodology studies demonstrate that alkyl-capped, asymmetric, internal alkynes undergo a regiospecific hydration, also via the 5-exo-dig NGP pathway.
烯烃的碘介导水合反应是一种绿色替代金属催化程序的方法。先前的研究表明,该方法在酮功能化支架上的末端烯烃,包括1,3-二羰基和其杂原子类似物中效果良好。假设该反应通过5-exo-dig 邻基参与(NGP)环化和α-碘中间体进行。本文所述的工作通过NMR研究探讨了中间体的存在,并探索了内部烯烃的水合作用范围。NMR实验证实了α-碘中间体的存在,并且方法学研究表明,带有烷基端基、不对称的内部烯烃通过5-exo-dig NGP途径进行特定区域的水合作用。