Photoredox-catalysed regioselective synthesis of C-4-alkylated pyridines with <i>N</i>-(acyloxy)phthalimides
作者:Zhucheng Zhang、Qian He、Xiaofei Zhang、Chunhao Yang
DOI:10.1039/d2ob00123c
日期:——
method of direct C-4 selective alkylation of pyridines under visible light irradiation at room temperature has been reported, using simple maleate-derived pyridinium salts as pyridine precursors and the readily available carboxylic acid-derived N-(acyloxy)phthalimides as alkyl radical precursors, affording good to excellent yields without using stoichiometric oxidants and acids. A broad range of primary
Regiodivergent Conversion of Alkenes to Branched or Linear Alkylpyridines
作者:Minseok Kim、Sanghoon Shin、Yejin Koo、Sungwoo Jung、Sungwoo Hong
DOI:10.1021/acs.orglett.1c04156
日期:2022.1.21
Herein we report a practical protocol for the visible-light-induced regiodivergent radical hydropyridylation of unactivated alkenes using pyridiniumsalts. This approach provides a unified synthetic platform to control the regioselectivity of the synthesis of linear or branched C4-alkylated pyridines. A remarkable selectivity switch from the anti-Markovnikov to the Markovnikov product can be achieved
Continuous Flow Preparation of Benzylic Sodium Organometallics
作者:Johannes H. Harenberg、Rajasekar Reddy Annapureddy、Konstantin Karaghiosoff、Paul Knochel
DOI:10.1002/anie.202203807
日期:2022.7.25
A lateral sodiation of alkyl(hetero)arenes using on-demand generated (2-ethylhexyl)sodium in the presence of TMEDA is reported. Various electrophiles were used for trapping of the benzyl sodium species generated in continuous flow as well as in batch. The continuous flow metalation was scaled-up using an in-line quench. The method was used in the synthesis of several industrial relevant compounds.
C4-selective decyanoalkylation has been established to access diverse 4-alkylpyridines in one step. The reaction proceeds through the single electron reduction/radical–radical coupling tandem process under mild electrolytic conditions, achieving the cleavage of the C(sp2)–CN bond and the formation of C(sp3)–C(sp2). The practicality of this protocol is illustrated by no sacrificial anodes, a broad substrate