Synthesis And Application Of Chiral Tridentate Pincer Ligand Based On Carbazole Framework

The asymmetric catalytic reaction involving transition metals is one of the hotspots in modern science research.The design of efficient and multifunctional ligands and their complexes is one of the main ways to improve the activity and enantio selectivity of asymmetric catalytic reactions.Among them,chiral ligands control the catalytic activity and stereoselectivity of metal complexes by adjusting their own electrical properties and stereoscopic effects.Therefore,the design and synthesis of new chiral ligands and their metal complexes in the field of asymmetric organic synthesis can provide more means to solve the problem.This article mainly introduces the synthesis of chiral three-tooth clamp ligands based on carbazole skeleton and its application in asymmetric catalytic reactions:1.Design,synthesis and characterization of chiral tridentate ligands and their complexes based on carbazole skeleton.Using the synthesis strategy of chiral phosphine compounds previously designed and developed by our group,different types（PNP,PNN and NNN）of chiral tridentate ligands and their complexes based on carbazole skeleton were designed and synthesized,and the synthesized ligands and their complexes were characterized by data.2.Application of chiral tri-dentate pincer ligands based on carbazole framework in cucatalyzed asymmetric 1,2-carbynylation of terminal alkenes.At room temperature,the asymmetric Sonogashira coupling reaction of terminal alkynes with alkyl halides was catalyzed by 2.0 equivalent cesium carbonate,5.0 mol%cuprous iodide,and 5.0 mol%chiral tridentate pincer-shaped PNN ligands based on carbazole skeleton in acetonitrile.The chiral alkyne compounds were obtained in 95%yield and 99%ee.3.Application of chiral tridentate ligand based on carbazole skeleton in copper-catalyzed 1,2-carbon alkyneylation of terminal olefins.At room temperature,2.0 equivalent cesium carbonate,10 mol%tetraacetonitrile copper hexafluorophosphate and 10 mol%chiral tridentate-clamped PNN ligand based on carbazole skeleton were used to catalyze the 1.2carbon alkyne reaction of terminal olefins,terminal alkynes and tert-butyl 2bromoisobutanoate in tetrahydrofuran solvent.The 1,2-carbon alkyne reaction of terminal olefins was achieved in moderate yield and good enantioselectivity.