A simple method for the synthesis of <i>N</i>-difluoromethylated pyridines and 4-pyridones/quinolones by using BrCF<sub>2</sub>COOEt as the difluoromethylation reagent
作者:Albert Gandioso、Mohamed El Fakiri、Anna Rovira、Vicente Marchán
DOI:10.1039/d0ra06322c
日期:——
We describe a novel transition metal-free method for the synthesis of N-difluoromethylated pyridines and 4-pyridones/quinolones by using readily available ethyl bromodifluoroacetate as a fluorine source. The formation of N-difluoromethylated pyridines involves a two-step process in which N-alkylation by ethyl bromodifluoroacetate is followed by in situ hydrolysis of the ester and decarboxylation. Besides
Direct Synthesis of <i>N</i>-Difluoromethyl-2-pyridones from Pyridines
作者:Sen Zhou、Xiaoya Hou、Kai Yang、Minjie Guo、Wentao Zhao、Xiangyang Tang、Guangwei Wang
DOI:10.1021/acs.joc.1c00228
日期:2021.5.7
A novel method for the synthesis of N-difluoromethyl-2-pyridones was described. This protocol enables the synthesis of N-difluoromethyl-2-pyridones from readily available pyridines using mild reaction conditions that are compatible with a wide range of functional groups. The preliminary mechanistic study revealed that N-difluoromethylpyridinium salts were the key intermediates to complete this conversion
A practical, convenient, and general method for the difluoromethylation of tertiary amines, using diethyl bromodifluoromethylphosphonate and fluoride, is described. This commercially available phosphonate smoothly reacts with a fluoride ion to liberate a difluorocarbene intermediate that in the presence of a proton source and a tertiary amine generates the corresponding α-difluoromethylammonium compound
Metal-Free Difunctionalization of Pyridines: Selective Construction of <i>N</i>-CF<sub>2</sub>H and <i>N</i>-CHO Dihydropyridines
作者:Sen Zhou、Ze-Ying Sun、Kongying Zhu、Wentao Zhao、Xiangyang Tang、Minjie Guo、Guangwei Wang
DOI:10.1021/acs.orglett.1c00352
日期:2021.3.19
N-difluoromethylpyridinium salts is seldom explored because of their instability and low availability. Here we present a novel nucleophilic addition of N-difluoromethylpyridinium salts with nitroalkanes to synthesize N-CF2H-dihydropyridines and N-CHO-dihydropyridines in a highly efficient and regioselective pathway. This protocol exhibits good functional group tolerance and good to excellent yields.