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。
Selective esterifications of alcohols and phenols through carbodiimide couplingsElectronic supplementary information (ESI) available: the characterization of new compounds and literature references for known compounds. See http://www.rsc.org/suppdata/ob/b3/b312559a/
作者:Rimma Shelkov、Moshe Nahmany、Artem Melman
DOI:10.1039/b312559a
日期:——
Esterification of carboxylic acids capable of forming ketene intermediates upon treatment with carbodiimides permits the selectiveacylation of alcohols in the presence of phenols lacking strong electron-withdrawing groups. The selectivity of acylations involving highly acidic phenols could be reversed through the addition of catalytic amount of acid. Esterification of other carboxylic acids was found