Functionalization Of C-H Adjacent To Nitrogen By Merging Photoredox Catalysis With Nucleophilic Catalysis

The application of light energy has become more and more important since the enviroment pollution. As a green and clean energy, light is used to mediate chemical reaction in photoredox catalysis.Nitrogen is an important part in amino acids and pharmacological agents which have great biological activity. Functionalization of C-H bond adjacent to nitrogen can realize modification and transformation of these important molecules which contain nitrogen. Tetrahydroisoquinolines(THIQ) are always used as a platform for C-H bond functionalization. Alkylation, alkynylation, arylation, cyanation, carbonylation and constrction of C-P bond, C-N bond, C-O bond have been complete by merging photoredox catalysis and other catalytic models to realize C-H bond functionalization of amine which has become a hot realm. A literature survey showed that there is no report of merging photoredox catalysis and nucleophilic catalysis. We have combined photoredox catalysis and nucleophilic catalysis to realize acroleination and allylation of C-H bond of tetrahydroisoquinolines.We have successfully realized C-H bond acroleination of THIQs by using α,β-unsaturated olefin as the nucleophilic reagent, DABCO as the nucleophilic catalyst. We successively investigated the influence of different photoredox catalysts, nucleophilic catalysts, bases, solvents, substituent effects and the amount of catalysts in the reaction. The reaction allows efficient access to C-H bond acroleination in 52-93% yield. Moreover, we have used chiral tertiary amine as the nucleophilic catalyst and obtained chiral products in good enantioselectivity (66% and 56% ee).The products have characterized by NMR, MS, IR and HRMS. The absolute configuration of the product is confimd to be (S) by specific rotation compared with previous report.We have successfully realized C-H bond allylation of THIQs by merging photoredox catalysis and palladium catalysis. Following our previous work, we have successfully replace palladium by KI. However, the catalytic modes is totally undifferent since KI is a nucleophilic catalyst. We proposed a radical-radical cross coupling mechanism based on literature report and our results.