Jandial Tanvi, Gupta Anish, Tsering Dolma, Kapoor Kamal K, Sridharan Vellaisamy
Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, J&K, Jammu 181143, India.
Department of Chemistry, University of Jammu, J&K, Jammu 180006, India.
J Org Chem. 2024 Sep 20;89(18):12989-13004. doi: 10.1021/acs.joc.4c01011. Epub 2024 Sep 4.
A nucleopalladation-triggered cascade transformation of internal alkynes bearing an amino nucleophile and an electrophilic enone was investigated under unconventional microwave-assisted conditions. Among the three possible pathways, the chloropalladation-triggered domino process proceeded selectively to furnish 3-chloro-1-indenes in good to excellent yields. The reactions under microwave irradiation were completed in 30 min, and the conventional heating required 3-5 h for completion. The yields obtained under nonclassical heating using microwave irradiation are marginally higher (71-97%) than those of the conventional heating conditions (67-96%). The mechanism of this domino process involves chloropalladation of alkynes to deliver σ-vinylpalladium intermediates, intramolecular carbopalladation via Heck-type olefin insertion, and protodepalladation steps. The other two competitive intramolecular aminopalladation-initiated cascades via 7- or 6- cyclizations leading to oxazepine or benzoxazine scaffolds were not observed.
在非常规微波辅助条件下，研究了带有氨基亲核试剂和亲电烯酮的内炔烃的核钯化引发的级联转化反应。在三种可能的途径中，氯钯化引发的多米诺过程选择性地进行，以良好至优异的产率提供3-氯-1-茚。微波辐射下的反应在30分钟内完成，传统加热则需要3-5小时才能完成。使用微波辐射的非经典加热条件下获得的产率略高于传统加热条件下的产率（71-97%对67-96%）。该多米诺过程的机理包括炔烃的氯钯化以生成σ-乙烯基钯中间体、通过Heck型烯烃插入进行分子内碳钯化以及质子脱钯步骤。未观察到另外两种通过7-或6-环化导致恶唑并[4,5-b]氮杂卓或苯并恶嗪支架的竞争性分子内氨基钯化引发的级联反应。
