Kreuzahler Mathis, Haberhauer Gebhard
Institut für Organische Chemie , Universität Duisburg-Essen , Universitätsstr. 7 , D-45117 Essen , Germany.
J Org Chem. 2019 Jun 21;84(12):8210-8224. doi: 10.1021/acs.joc.9b01371. Epub 2019 Jun 13.
The haloalkynylation reaction is of great interest for the synthesis of complex molecules as it represents a carbon-carbon bond-forming reaction where the reactive halide reappears in the product. The latter enables further chemical transformations. However, only a few examples of haloalkynylations have been described so far. By using alkenes as reactant, this reaction is strictly limited to norbornene systems proceeding via a nonclassical carbocation. Herein, we show by means of quantum chemical calculations and experiments that the chloroalkynylation of 1,1-disubstituted alkenes can be successfully achieved via gold(I) catalysis. The key step in the reaction mechanism is a 1,3-chlorine shift to a cationic center, leading selectively to the corresponding homopropargyl chlorides. As this gold(I)-catalyzed addition can be conducted on a preparative scale and tolerates a broad substrate scope of both alkyne and alkene reactants, the presented chloroalkynylation reaction is an attractive method en route to complex alkynes and their congeners.
卤代炔基化反应对于复杂分子的合成具有重要意义，因为它代表了一种碳-碳键形成反应，其中反应性卤化物会在产物中再次出现。这使得进一步的化学转化成为可能。然而，到目前为止，仅报道了少数卤代炔基化的例子。以烯烃作为反应物时，该反应严格限于通过非经典碳正离子进行的降冰片烯体系。在此，我们通过量子化学计算和实验表明，1,1-二取代烯烃的氯代炔基化反应可以通过金（I）催化成功实现。反应机理中的关键步骤是1,3-氯迁移至阳离子中心，选择性地生成相应的高炔丙基氯。由于这种金（I）催化的加成反应可以在制备规模上进行，并且对炔烃和烯烃反应物的广泛底物范围具有耐受性，因此所提出的氯代炔基化反应是合成复杂炔烃及其同系物的一种有吸引力的方法。
