自由基从双环[2.2.0]己烷中的桥位和桥头位都提取氢(4)。通过epr光谱法观察到双环[2.2.0]己烷-1-基。双环[2.2.0]己-2-基通过立体电子禁止的β-断裂重排,得到环己-3-烯基。与其他环丁烷不同,化合物(4)与溴原子进行S H 2反应。自由基夺取氢仅从C的亚甲基基团5环双环[3.2.0]庚烷(15A)。通过epr光谱法观察到双环[3.2.0]庚-2-基,以及通过立体电子允许的β-断裂将其重排为2-(环戊-2-烯基)乙基。溴原子从(15a)提取氢,未检测到S H 2反应。使用半经验MINDO / 3和MNDO方法研究了自由基及其重排。
Iron-Catalyzed [2π + 2π] Cycloaddition of α,ω-Dienes: The Importance of Redox-Active Supporting Ligands
摘要:
The bis(imino)pyridine iron bis(dinitrogen) complex, (iPrPDI)Fe(N2)2 (iPrPDI = 2,6-(2,6-iPr2C6H3NCR)2C5H3N), serves as an efficient precursor for the catalytic [2pi + 2pi] cycloaddition of alpha,omega-dienes to yield the corresponding bicycles. For amine substrates, the rate of catalytic turnover increases with the size of the nitrogen substituents, demonstrating competing heterocycle coordination and product inhibition. In one case, a bis(imino)pyridine iron azobicycloheptane product was characterized by X-ray diffraction. Preliminary mechanistic studies highlight the importance of the redox activity of the bis(imino)pyridine ligand to maintain the ferrous oxidation state throughout the catalytic cycle.
Homolytic rearrangements of bicyclo[2.2.0]hexane and bicyclo[3.2.0]heptane
作者:John C. Walton
DOI:10.1039/p29880001371
日期:——
methylene groups of the C5 ring in bicyclo[3.2.0]heptane (15a). The bicyclo[3.2.0]heptan-2-yl radicals were observed by e.p.r. spectroscopy, as was their rearrangement, by stereoelectronically allowed β-scission, to 2-(cyclopent-2-enyl)ethyl radicals. Bromine atoms abstract hydrogen from (15a) and no SH2 reaction was detected. The radicals and their rearrangements were studied by semi-empirical MINDO/3
自由基从双环[2.2.0]己烷中的桥位和桥头位都提取氢(4)。通过epr光谱法观察到双环[2.2.0]己烷-1-基。双环[2.2.0]己-2-基通过立体电子禁止的β-断裂重排,得到环己-3-烯基。与其他环丁烷不同,化合物(4)与溴原子进行S H 2反应。自由基夺取氢仅从C的亚甲基基团5环双环[3.2.0]庚烷(15A)。通过epr光谱法观察到双环[3.2.0]庚-2-基,以及通过立体电子允许的β-断裂将其重排为2-(环戊-2-烯基)乙基。溴原子从(15a)提取氢,未检测到S H 2反应。使用半经验MINDO / 3和MNDO方法研究了自由基及其重排。
Iron-Catalyzed [2π + 2π] Cycloaddition of α,ω-Dienes: The Importance of Redox-Active Supporting Ligands
作者:Marco W. Bouwkamp、Amanda C. Bowman、Emil Lobkovsky、Paul J. Chirik
DOI:10.1021/ja064711u
日期:2006.10.1
The bis(imino)pyridine iron bis(dinitrogen) complex, (iPrPDI)Fe(N2)2 (iPrPDI = 2,6-(2,6-iPr2C6H3NCR)2C5H3N), serves as an efficient precursor for the catalytic [2pi + 2pi] cycloaddition of alpha,omega-dienes to yield the corresponding bicycles. For amine substrates, the rate of catalytic turnover increases with the size of the nitrogen substituents, demonstrating competing heterocycle coordination and product inhibition. In one case, a bis(imino)pyridine iron azobicycloheptane product was characterized by X-ray diffraction. Preliminary mechanistic studies highlight the importance of the redox activity of the bis(imino)pyridine ligand to maintain the ferrous oxidation state throughout the catalytic cycle.