Mass spectrometric studies of cyclopropanes with electronegative substituents. Indication of methoxy group randomization in (±) dimethyl 2-methoxy-3,3-dimethylcyclopropane-1,1-dicarboxylate
摘要:
Abstract(±) 2‐Methoxy‐3,3‐dimethylcyclopropane‐1,1‐carboxylate was studied by electron impact and chemical ionization mass spectrometry. By using selective deuteration of the methyl groups, it was established that extensive randomization of the methoxy groups takes place prior to the decomposition of the molecular ion.
Nonproductive Events in Ring-Closing Metathesis Using Ruthenium Catalysts
作者:Ian C. Stewart、Benjamin K. Keitz、Kevin M. Kuhn、Renee M. Thomas、Robert H. Grubbs
DOI:10.1021/ja1029045
日期:2010.6.30
and nonproductive metathesis reactions of diethyl diallylmalonate are compared for eight different ruthenium-based catalysts. Nonproductive cross metathesis is proposed to involve a chain-carrying ruthenium methylidene. A second more-challenging substrate (dimethyl allylmethylallylmalonate) that forms a trisubstituted olefin product is used to further delineate the effect of catalyst structure on the
A Convenient One-Step Synthesis of Ethyl 2-[<i>N</i>-(Diethoxycarbonyl)(ethoxy)-methyl]amino-4-nitrobenzoate and Analogues by Rearrangement of 2,4-Dinitrobenzylidenemalonates
作者:Stefan Kinastowski、Stanisław Wnuk
DOI:10.1055/s-1983-30462
日期:——
KINASTOWSKI, S.;WNUK, S., SYNTHESIS, BRD, 1983, N 8, 654-659
作者:KINASTOWSKI, S.、WNUK, S.
DOI:——
日期:——
Gas-Phase Synthesis of Charged Copper and Silver Fischer Carbenes from Diazomalonates: Mechanistic and Conformational Considerations in Metal-Mediated Wolff Rearrangements
作者:Ryan R. Julian、Jeremy A. May、Brian M. Stoltz、J. L. Beauchamp
DOI:10.1021/ja028337j
日期:2003.4.1
products. Silver(I) is shown to be more effective in facilitating Wolffrearrangement than copper(I), although both are more effective when compared to spectator charges such as sodium or a fixed quaternary nitrogen. Carbenes are not produced when copper(II), nickel(II), or a proton is used to form a quasi-molecular ion from the diazomalonate carbene precursor. Finally, trapping of the Fischer carbene by
铜 (I) 和银 (I) Fischer 卡宾在气相中合成。通过电喷雾电离将各种具有附着金属离子的重氮丙二酸酯基化合物引入气相并进行碰撞活化。N(2) 的损失生成亚稳态费舍尔卡宾,随后经历沃尔夫重排和 CO 的损失。进一步激发导致另一个 CO 分子的损失和稳定的费舍尔卡宾的生成。同位素标记的化合物用于确认该过程产生的产物的归属。DFT 计算用于评估各种机械可能性并定量评估反应物和产物的能量。银(I)被证明在促进沃尔夫重排方面比铜(I)更有效,尽管与钠或固定季氮等旁观者费用相比,两者都更有效。当使用铜 (II)、镍 (II) 或质子从重氮丙二酸酯卡宾前体形成准分子离子时,不会产生卡宾。最后,研究了通过金属的开放配位位点连接的各种官能团对 Fischer 卡宾的捕获。
Mass spectrometric studies of cyclopropanes with electronegative substituents. Indication of methoxy group randomization in (±) dimethyl 2-methoxy-3,3-dimethylcyclopropane-1,1-dicarboxylate
Abstract(±) 2‐Methoxy‐3,3‐dimethylcyclopropane‐1,1‐carboxylate was studied by electron impact and chemical ionization mass spectrometry. By using selective deuteration of the methyl groups, it was established that extensive randomization of the methoxy groups takes place prior to the decomposition of the molecular ion.