The iodocyclisation of alkynes bearing tethered nucleophiles is a highly effective method for the construction and diversification of heterocycles. A key limitation to this methodology is the 5-endo-dig iodocyclisation of alkynes that have an unfavourable electronic bias for electrophilic cyclisation. These tend to direct electrophilic attack of the iodonium atom to the wrong carbon for cyclisation, thus favouring competing addition reactions. Using our previously determined reaction conditions for the 5-endo-dig iodocyclisations of electronically resistant alkynes, we have achieved efficient synthetic access to 2-carboxy (and sulfoxy)-3-iodobenzo[b]thiophenes. The corresponding benzo[b]furans and indoles were not accessible under these conditions. This difference may arise due to the availability of a radical mechanism in the case of iodobenzo[b]thiophenes. The 2-carboxy functionality of the iodocyclised products can be further employed in iterative alkyne-coupling iodocyclisation reactions, where the carboxy group or an imine (Schiff base) partakes in a second iodocyclisation to generate a lactone or pyridine ring.

带有拴系亲核试剂的炔烃的碘环化是构建和多样化杂环的高效方法。该方法的主要局限性是炔类化合物的5 -endo-dig碘环化，它对亲电环化有不利的电子偏倚。这些趋向于将碘鎓原子的亲电子攻击指向错误的碳以进行环化，因此有利于竞争性加成反应。使用我们先前确定的用于电子耐性炔烃的5-内切式碘环化的反应条件，我们已经成功合成了2-羧基（和亚砜氧基）-3-碘代苯并[ b ]噻吩的合成途径。相应的苯并[ b在这些条件下无法获得呋喃和吲哚。这种差异可能是由于在碘代苯并[ b ]噻吩的情况下可利用自由基机理而引起的。碘环化产物的2-羧基官能度可进一步用于迭代炔烃偶联碘环化反应中，其中羧基或亚胺（席夫碱）参与第二次碘环化以生成内酯或吡啶环。