Base catalysed rearrangement of N-alkyl-O-acyl hydroxamic acids: synthesis of 2-acyloxyamides
作者:Andrew J. Clark、Yassair S. S. Al-Faiyz、Michael J. Broadhurst、Divya Patel、Joanne L. Peacock
DOI:10.1039/a909903d
日期:——
Activated N-alkyl-O-acyl hydroxamic acid derivatives 21a–t undergo thermal and base catalysed rearrangement to give 2-acyloxyamides 22a–t in good to excellent yields (50–100%). A range of inorganic and organic bases were screened for their efficiency in mediating the rearrangement 21 to 22, however, simple organic bases such as Et3N were found to be the most efficient. Both aromatic and aliphatic derived
活化的N-烷基-O-酰基异羟肟酸衍生物21a–t经过热催化和碱催化重排,以良好的产率(50–100%)得到2-酰氧基酰胺22a–t。筛选了一系列无机和有机碱以介导重排21至22的效率,但是,发现简单的有机碱(例如Et 3 N)是最有效的。在该反应中,芳族和脂族衍生的O-酰基均被耐受。发现O-酰基的电子性质会影响吸电子基团的重排速率(21l和21o)增加了观察速率,而给电子基团(21m和21n)降低了观察速率。与21a和21h的交叉实验表明了涉及游离酰氧基阴离子中间体的机理。容易浮雕的要求质子 毗邻 羰基 的 酰胺由于在所研究的反应条件下21r和21t均不能重排,因此发现对于重排是必要的。