PRODUCTS AND KINETICS OF DECARBOXYLATION OF ACTIVATED AND UNACTIVATED AROMATIC CUPROUS CARBOXYLATES IN PYRIDINE AND IN QUINOLINE
PRODUCTS AND KINETICS OF DECARBOXYLATION OF ACTIVATED AND UNACTIVATED AROMATIC CUPROUS CARBOXYLATES IN PYRIDINE AND IN QUINOLINE
复制标题
DOI：
10.1021/jo00399a010
复制
发表时间：
1978-01-01
影响因子：
3.6
通讯作者：
WOOD, JT
中科院分区：
文献类型：
--
作者：
COHEN, T;BERNINGER, RW;WOOD, JT
在脱羧溶剂中，用铜还原铜盐，可以制备出芳香亚铜羧酸盐，并对其在喹啉和吡啶中的脱羧反应进行动力学和产物研究。所得结果与用叔丁二氧化亚铜处理酸制得的相同的盐所得的结果没有区别，后者是一个更繁琐的过程。除邻硝基苯甲酸亚铜为Ar2外，ArC02Cu脱羧反应的主要中性产物为ArH，除二氧化碳外。取代羧基的氢似乎主要来自溶剂，并在芳基取代到溶剂分子和溶剂分子偶联过程中释放出来。在喹啉中，后一类产品主要由双喹啉和一些氧双喹啉组成。由于从所有芳香盐的脱羧和在喹啉中加热五氟苯基铜得到的溶剂分离产物组成大致相同，因此可以认为涉及芳基铜和喹基铜中间体；这是此类中间体在非活化亚铜羧酸盐的情况下的第一个证据。这些中间体，干净的一级动力学，反对自由基过程的证据，以及该反应与乌尔曼偶联以及铜诱导的交换过程之间在取代基、溶剂和配体效应方面的相似性，导致了一种新的机制建议，即羧基CC键氧化加成到铜-per®上，然后损失二氧化碳。提出了一种制备2-氘喹啉的有效方法，并对2,2′-二氟苯甲酮的250 mhz谱进行了几乎完整的分析。
Aromatic cuprous carboxylates can be prepared in a state suitablefor kinetic and product studies of their decar-boxylations in quinoline and pyridine by reducing the cupric salt with copper in the decarboxylation solvent. The results were indistinguishable from those obtainedfrom the same salts prepared by treatment of the acids with cu-prous tert-butoxide, a more tedious procedure. The major neutral product, besides carbon dioxide, for the decar-boxylation of ArC02Cu is ArH except in the case of cuprous o-nitrobenzoate in which it is Ar2. The hydrogen which replaces the carboxyl group appears to be derived largelyfrom the solvent and is released during the substitution of aryl groups into solventmolecules and the couplingof solventmolecules. In quinoline, the latter type of product consists mainly of biquinolyls and some oxybiquinolyls. Since approximately the same composition of solvent-de-rived products is obtained from the decarboxylations of all of the aromatic salts and by heating pentafluorophenyl-copper in quinoline, it is believed that arylcopper and quinolylcopper intermediates are involved; this is the first evidence for such intermediatesin the case of nonactivated cuprous carboxylates. Such intermediates, the clean first-order kinetics, evidence against a radical process, and the similarity with respect to substituent, solvent, and ligand effects between this reaction and the Ullmann biaryl coupling as well as copper-induced exchange processes lead to a new mechanistic suggestion which involves an oxidative addition of the carboxyl CC bond to the cop-per® followed by loss of carbon dioxide. Anefficient method of preparation of 2-deuterioquinoline is presented, as is a nearly complete analysis of the 250-MHz spectrum of 2, 2'-difluorobenzophenone.