Hydrogen-carbon, carbon-carbon double rearrangement induced by proximity effects. 1-formation of methoxybenzyl ions in the electron impact mass spectra of substituted 1,1-bis(dimethoxyphenyl)methanes
AbstractThe 75 eV electron impact mass spectra of 1,1‐bis(dimethoxyphenyl)methanes bearing o‐methoxy groups are dominated by intense peaks corresponding, at least formally, to benzyl ions [(CH3O)2C6H3CH2]+(b). They arise from ions [((CH3O)2C6H3)2CH]+(a), which are in turn formed from molecular ions by loss of an alkyl radical through benzylic cleavage. The analysis of compounds labelled with 2H or 13C at methoxy groups led to the determination of the mechanism. Hydrogen migration, as hydride, followed by electrophilic substitution by the methylene carbon of the phenyl methylene ether cation through a six‐centred transition state is responsible for the formation of benzylic ions b.
Mandelonitrile in synthesis of partially hydrogenated isoquinoline derivatives
作者:A. V. Kharitonova、A. A. Gorbunov、Yu. V. Shklyaev
DOI:10.1134/s107042721008032x
日期:2010.8
New procedures for preparing tetrahydroisoquinoline derivatives using available chemicals are described.
Solvent Dependence of the Monomer–Dimer Equilibrium of Ketone‐Substituted Triscatecholate Titanium(IV) Complexes
作者:A. Carel N. Kwamen、Judith Jenniches、Iris M. Oppel、Markus Albrecht
DOI:10.1002/chem.202001053
日期:2020.8.17
Hierarchical helicates based on ketone‐substituted titanium(IV)triscatecholates show different monomer‐dimer behavior depending on different solvents. The dimerization constants of a whole series of differently alkyl‐substituted complexes is analyzed to show that the solvent has a very strong influence on the dimerization. Hereby, effects like solvophobicity/philicity, sterics, electronics of the substituents
Hierarchical Assembly of Helicate-Type Dinuclear Titanium(IV) Complexes
作者:Markus Albrecht、Sebastian Mirtschin、Marita de Groot、Ingo Janser、Jan Runsink、Gerhard Raabe、Michael Kogej、Christoph A. Schalley、Roland Fröhlich
DOI:10.1021/ja052326j
日期:2005.7.1
The ligands 4-7-H(2) were used in coordination studies with titanium(IV) and gallium(III) ions to obtain dimeric complexes Li(4)[(4-7)(6)Ti(2)] and Li(6)[(4/5a)(6)Ga(2)]. The X-ray crystal structures of Li(4)[(4)(6)Ti(2)], Li(4)[(5b)(6)Ti(2)], and Li(4)[(7a)(6)Ti(2)] could be obtained. While these complexes are triply lithium-bridged dimers in the solid state, a monomer/dimer equilibrium is observed
配体 4-7-H(2) 用于与钛 (IV) 和镓 (III) 离子的配位研究,以获得二聚体配合物 Li(4)[(4-7)(6)Ti(2)] 和 Li (6)[(4/5a)(6)Ga(2)]。Li(4)[(4)(6)Ti(2)]、Li(4)[(5b)(6)Ti(2)]和Li(4)[(7a)的X射线晶体结构(6)Ti(2)] 可以得到。虽然这些复合物是固态的三重锂桥二聚体,但通过 NMR 光谱和 ESI FT-ICR MS 观察到溶液中的单体/二聚体平衡。二聚体的稳定性通过单体的高负电荷(Ti(IV) 与 Ga(III))增强,当羰基单元是良好的供体(醛与酮和酯)时,当溶剂不能有效地溶剂化桥接时锂离子(DMSO 与丙酮),以及当空间位阻最小时(甲基与伯和仲碳取代基)。二聚体在热力学上受到焓和熵的青睐。ESI FT-ICR 质谱提供了对单体三儿茶酚酸酯复合物以及单儿茶酚配体在二聚体中交换的机制的