Jandial Tanvi, Gupta Anish, Jan Gowsia, Karuppasamy Muthu, Nagarajan Subbiah, Maheswari C Uma, Sridharan Vellaisamy
Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu-181143, J&K, India.
Department of Chemistry, National Institute of Technology, Warangal, Warangal-506004, Telangana, India.
Org Biomol Chem. 2023 Apr 12;21(15):3121-3131. doi: 10.1039/d3ob00041a.
A microwave-assisted, palladium(II)-catalyzed cascade reaction of 2-alkynylanilines tethered with an α,β-unsaturated carbonyl moiety was established to access 5,10-dihydroindeno[1,2-]indoles in high yields (up to 84%) in a short reaction time. This operationally simple cascade process shows 100% atom economy and allows the construction of two new five-membered rings and two new (1 C-C and 1 C-N) bonds in a single synthetic attempt. The mechanistic pathway of this reaction is visualized involving intramolecular aminopalladation (5-) followed by carbopalladation (olefin insertion) and protonolysis steps. A systematic comparison between microwave irradiation and conventional heating methods was also performed to demonstrate the supremacy of the microwave-assisted approach. This domino reaction requires no protecting groups for the amino group and the palladium catalyst needs no ligands. To the best of our knowledge, this is the first report on microwave-assisted nucleopalladation-initiated cascade transformation.
建立了一种微波辅助、钯（II）催化的、带有α，β-不饱和羰基部分的2-炔基苯胺的串联反应，可在短反应时间内高产率（高达84%）地得到5,10-二氢茚并[1,2-]吲哚。这个操作简单的串联过程显示出100%的原子经济性，并且能够在一次合成尝试中构建两个新的五元环和两个新的（1个C-C和1个C-N）键。该反应的机理途径可设想为涉及分子内氨基钯化（5-），随后是碳钯化（烯烃插入）和质子解步骤。还对微波辐射和传统加热方法进行了系统比较，以证明微波辅助方法的优越性。这种多米诺反应不需要对氨基进行保护基团，钯催化剂也不需要配体。据我们所知，这是关于微波辅助的亲核钯化引发的串联转化的首次报道。
