Combination of PhI(OAc)<sub>2</sub> and 2-Nitropropane as the Source of Methyl Radical in Room-Temperature Metal-Free Oxidative Decarboxylation/Cyclization: Construction of 6-Methyl Phenanthridines and 1-Methyl Isoquinolines
A room-temperature metal-free method for generating highly unstable methyl radical was realized from the combination of PhI(OAc)2 and 2-nitropropane, which provides an efficient approach to methylated phenanthridines and isoquinolines. The strategy was also extended to the generation of other alkyl radicals and a concise synthesis of Roxadustat.
The methylation or trideuteromethylation reaction of isocyanides with dimethyl sulfoxides in a radical way is developed, which offers a low-cost, easy-operation cascade methylation strategy for the synthesis of phenanthridines or isoquinolines.
A method for the synthesis of phenanthridines from benzylamines and aryl iodides which uses a dual palladium-catalyzed process is developed. The domino sequence ends via an intramolecular amination and an oxidative dehydrogenation. No protecting group or prefunctionalization of the amine is required, and the process uses dioxygen as the terminal oxidant.
Free-Radical Triggered Ordered Domino Reaction: An Approach to C–C Bond Formation via Selective Functionalization of α-Hydroxyl-(sp<sup>3</sup>)C–H in Fluorinated Alcohols
作者:Zhengbao Xu、Zhaojia Hang、Zhong-Quan Liu
DOI:10.1021/acs.orglett.6b01946
日期:2016.9.16
free-radical mediated highly ordered radical addition/cyclization/(sp3)C–C(sp3) formation domino reaction is developed. Three new C–C bonds are formed one by one in a mixed system. Furthermore, it represents the first example of cascade C–C bond formation via selective functionalization of α-hydroxyl-C(sp3)–H in fluorinated alcohols.
A robust synthesis of phenanthridines has been described via Pd(II)-catalyzed domino C(sp2)–H activation/N-arylation using oxime esters with aryl acyl peroxides in a highly regioselective manner. This protocol is compatible with acetophenone as well as benzophenone-derived oxime esters and allows modular construction of functionalized phenanthridines with wide tolerance of electronic functionality