Sterically controlled C–H/C–H homocoupling of arenes <i>via</i> C–H borylation
作者:Xiaocong Pei、Guan Zhou、Xuejing Li、Yuchen Xu、Resmi C. Panicker、Rajavel Srinivasan
DOI:10.1039/c9ob00995g
日期:——
A mild one-pot protocol for the synthesis of symmetrical biaryls by sequential Ir-catalyzed C-H borylation and Cu-catalyzed homocoupling of arenes is described. The regiochemistry of the biaryl formed is sterically controlled as dictated by the C-H borylation step. The methodology is also successfully extended to heteroarenes. Some of the products obtained by this approach are impossible to obtain
Discrete, well-defined stacks of the polarized aromatic pyrene-4,5-dione (1) were assembled in the cavities of organic-pillaredcoordinationcages (2). The number (n) of stacked guests depends on the pillar length, and up to quintuple stacks (n = 5) were observed when long (16.5 A) organic pillar ligands were incorporated. As previously reported, pyrene-4,5-dione (1) assembles into infinite columnar
A 4,4'-bipyridine-based catalyst system for diboration of pyrazine derivatives was established. The catalyst cycle consists of the following two steps: (1) reductive addition of the boron-boron bond of bis(pinacolato)diboron to 4,4'-bipyridine to form N,N'-diboryl-4,4'-bipyridinylidene and (2) oxidative boryl transfer from the intermediate to pyrazine to give N,N'-diboryl-1,4-dihydropyrazine with regeneration
Cocondensation reactions of nitrogen-containing heterocycles with lithium atoms at 77 K
作者:Oscar Mendoza、Helge Müller-Bunz、Matthias Tacke
DOI:10.1016/j.jorganchem.2005.04.017
日期:2005.7
Lithiumatoms were cocondensed with aromatic nitrogen-containing heterocycles in the presence of THF at 77K. The reaction products in the case of the heterocyclic five-membered rings (imidazole) resulted in a C–H bond activation and led to the corresponding aryl lithium compound. Other heterocycles such as pyridine and pyrimidine led to the formation of a non-lithiated aromatic product, in which the