We report herein a visible light-mediated C-H hydroxyalkylation of quinolines and isoquinolines that proceeds via a radical path. The process exploits the excited-state reactivity of 4-acyl-1,4-dihydropyridines, which can readily generate acyl radicals upon blue light absorption. By avoiding the need for external oxidants, this radical-generating strategy enables a departure from the classical, oxidative
3-,4-Pyridyl and 4-quinolyl Grignardreagents were generated by the reaction of the corresponding phenyl sulfoxides with PhMgBr and give the adducts upon treatment with various aldehydes and ketones. The stereochemistry for the reaction was investigated.
[GRAPHICS]The high level of catalyst performance was attainable in the palladium-catalyzed 1,2-addition of aryl-, heteroaryl-, and alkenylboronic acids to aromatic, heteroaromatic, and aliphatic aldehydes using thioether-imidazolinium chloride L5 as a heterobidentate carbene ligand precursor.
Transition-Metal Free Chemoselective Hydroxylation and Hydroxylation–Deuteration of Heterobenzylic Methylenes
作者:Yonghai Liu、Yang Yu、Chengyu Sun、Yiwei Fu、Zhiguo Mang、Lei Shi、Hao Li
DOI:10.1021/acs.orglett.0c03108
日期:2020.10.16
We developed an approach for direct selective hydroxylation of heterobenzylic methylenes to secondary alcohols avoiding overoxidation to ketones by using a KOBu-t/DMSO/air system. Most reactions could reach completion in several minutes to give hydroxylated products in 41-76% yields. Using DMSO-d6, this protocol resulted in difunctionalization of heterobenzylic methylenes to afford α-deuterated secondary alcohols (>93% incorporation). By employing this method, active pharmaceutical ingredients carbinoxamine and doxylamine were synthesized in two steps in moderate yields.