How pyridine got its tail: A new catalyst for the atom‐economical C4‐selective direct alkylation of pyridines is described. A combination of CoBr2 and LiBEt3H catalyzes the reaction of pyridines with 1‐alkenes at 70 °C to give alkylation products with C4/C2 ratios of >20:1. Substrate/catalyst ratios of up to 4000, and a turnover number of 3440 were achieved.
Chromium-Catalyzed Regioselective Hydropyridination of Styrenes
作者:Yuexuan Li、Gongda Deng、Xiaoming Zeng
DOI:10.1021/acs.organomet.5b01021
日期:2016.3.14
The first chromium-catalyzed regioselective addition of para-C-H bonds, of pyridines across styrenes is disclosed. The hydrofunctionalization reaction was promoted by a low-cost chromium(III) chloride combining with a cyclohexyl Grignard reagent and 2,2'-bipyridine, which allows for the highly selective formation of branched products via the cleavage of inert C-H bonds Of pyridines.
WALTER L. A.; CHANG W. K.; MCGLOTTEN J.; FOESTER R., J. HETEROCYCLIC CHEM. <JHTC-AD>, 1977, 14, NO 1, 47-51
作者:WALTER L. A.、 CHANG W. K.、 MCGLOTTEN J.、 FOESTER R.
DOI:——
日期:——
Organoborohydride-catalyzed Chichibabin-type C4-position alkylation of pyridines with alkenes assisted by organoboranes
prior formation of N-activated pyridines, organometallic reagents, and extra oxidation operation for the construction of a C–C bond at the C4-position of the pyridines in previous methods are not required. The corresponding mechanism and the key roles of the organoborane were elaborated by the combination of H/D scrambling experiments, 11B NMR studies, intermediate trapping experiments and computational
第一NaBEt 3 H-催化分子间吡啶Chichibabin型烷基化和其与烯烃作为潜亲核试剂衍生物呈现BET的协助3,以及一系列支链C4烷基化吡啶,即使高度拥塞全碳季中心含-三芳基甲烷可以以区域特异性方式获得。因此,传统上依赖于高成本和低可用性的过渡金属催化剂,先形成N活化的吡啶,有机金属试剂和在以前方法中不需要额外的氧化操作来在吡啶的C4位上构建C–C键。H / D加扰实验,11 B NMR研究,中间捕获实验和计算研究相结合详细阐述了有机硼烷的相应机理和关键作用。这种直接的,机械上独特的有机催化技术不仅为经典的但仍未得到很好开发的奇奇巴宾型反应打开一扇新门,而且为开发新型C–C键形成方法建立了新平台。