作者:Rebecca J. Burns、Ioulia K. Mati、Kamila B. Muchowska、Catherine Adam、Scott L. Cockroft
DOI:10.1002/anie.202006943
日期:2020.9.14
were transposed onto the Hammett substituent constant scale revealing dominant through‐space substituenteffects that cannot be described in classic terms. For example, NO2 groups positioned over a biaryl bond exhibited similar influences as resonant electron donors. Meanwhile, the electro‐enhancing influence of OMe/OH groups could be switched off or inverted by conformational twisting. 267 conformational
The electrophilic behavior of the reactive entity in the phtosubstitution of benzenes with 2-iodopyridine was found to be ascribable to the intermediary 2-pyridyl cation, rather than to the electrophilic 2-pyridyl radical.
Synthetic applications of N-N linked heterocycles. Part 7. The preparation of 4-alkyl- and 4-aryl-pyridines by regiospecific attack of Grignard reagents ? to quaternary nitrogen in N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts
作者:Alan R. Katritzky、Hector Beltrami、Michael P. Sammes
DOI:10.1039/p19800002480
日期:——
N-(2,6-Dimethyl-4-oxopyridin-1-yl)pyridinium salts (4), new reagents for the regiospecific synthesis of 4-substituted pyridines, give moderate to high yields of 4-alkyl- and 4-aryl-pyridines (8)–(10) on reaction with Grignard reagents. The scope and limitations of the reaction, which proceeds via 1,4-dihydro-intermediates (5)–(7), are explored. No 2-substituted pyridines were detected. Some reactions
Pyridino-directed lithiation of anisylpyridines: new access to functional pyridylphenols
作者:Michaël Parmentier、Philippe Gros、Yves Fort
DOI:10.1016/j.tet.2004.10.100
日期:2005.3
The lithiation of nine anisylpyridines has been studied. While usual reagents did not react or gave addition products on pyridine ring, the BuLi-LiDMAE (LiDMAE=Me2N(CH2)2OLi) superbase induced exclusive pyridino directedmetallation. The usefulness of this new reaction allowed the efficient preparation of a range of alpha functional pyridylphenols. A successful subsequent cyclisation of an appropriate
已经研究了九种茴香基吡啶的锂化。尽管通常的试剂在吡啶环上不发生反应或未提供加成产物,但BuLi-LiDMAE(LiDMAE = Me 2 N(CH 2)2 OLi)超碱诱导了吡啶基定向金属化反应。该新反应的有用性允许有效地制备一系列α官能的吡啶基酚。随后还成功地将合适的异构体成功环化为相应的苯并呋喃基吡啶。
Cobalt-catalyzed cross-coupling of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium reagents
Cobalt-catalyzed cross-couplings of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium halides proceeded efficiently with the aid of cobalt(II) catalyst and copper(I) salt in tetrahydrofuran at ambient temperature, producing the desired 4-arylated pyridine, quinoline, and quinoxaline in modest to good yields.
钴催化的含氮杂环鏻盐与芳基卤化镁的交叉偶联在钴 (II) 催化剂和铜 (I) 盐的帮助下在四氢呋喃中在环境温度下有效进行,产生所需的 4-芳基化吡啶、喹啉和喹喔啉产量适中至良好。