coupling of 9-bromoanthracene with acrolein acetals was studied. While the ester is the quasi exclusive product when only a base (i.e. NaOAc, K2CO3, etc.) is added in the medium, the presence of halide abstracting agent such as thallium or silver salts decreases noticeably the selectivity towards the ester. On the other hand, the addition of n-Bu4NOAc yields to the formation of the aldehyde with up to 74%
研究了几个参数对
钯催化的
9-溴蒽与
丙烯醛缩醛的Heck偶联选择性的影响。当在介质中仅添加碱(即NaOAc,K 2 CO 3等)时,酯是准排他的产物,而卤化物提取剂(例如al或
银盐)的存在则明显降低了对酯的选择性。另一方面,n -Bu 4的加法NOAc以高达74%的选择性生成
醛类。发现
水的存在不仅对反应速率而且对反应的选择性都起重要作用。提出了一种综合机制,概述了每种添加剂的影响,特别是对反应选择性的影响。