Study On Synthesis Of Quinoline-Fused Lactones By C_sp³-H Oxidation

Promoted by a radical cation salt, a domino oxidative Povarov reaction/aromatization/lactonization process was achieved, synthesizing a series of quinoline- fused lactones. Furthermore, C-H oxidation of N-alkylhydrazides and Friedel–Crafts reaction were also investigated. The details were listed below:1. Inspired by our fragment-reassembly strategy, a domino oxidative Povarov reaction/aromatization/lactoni-zation process was achieved, synthesizing a series of quinoline- fused lactones. This method provides a new way to construct biologically relevant polycycle skeleton, and is a good complement to the reported intramolecular variant of cinnamyl glycine esters. Due to the ring size, no lactone was obtained while 3,4-dihydro-2H-pyran was employed to react with glycine esters.2. The Friedel–Crafts reaction between glycine esters and 2,3-dihydrofuran was realized in the presence of radical cation salt and KI. The mechanistic stud ies show that this catalytic system is a kind of mild Lewis acid, system which is superior to iodine.3. The preliminary results of C-H oxidation and allylation of N-alkylhydrazines were reported. Mechanistic studies have revealed that N-acylhydrazone is a key intermediate in this catalytic transformation, and undergoes the followed allylation with allyltin reagents. This reaction is a kind of direct C-H allylation, which is worthy of further investigation.