The observation of remarkable effects of remotely connected but spatially proximate hydroxy-groups on the rates and regiochemistry of the birch reduction of aromatic rings and double bonds
作者:Evangelo Cotsaris、Michael N. Paddon-Row
DOI:10.1039/p29840001487
日期:——
competitive-rate studies of Birch reduction (Li, ButOH, NH3) of a series of alicyclic compounds, (6)–(13), are described. The hydrocarbons (6a)–(8a) and the syn-methoxy derivative (6c) are slowly reduced to give the unconjugated dienes such as (16a). In contrast the syn-alcohols (6b)–(8b)were rapidly reduced to give the monoenes (17),(19), and (22), respectively. Reduction of the syn-alcohol (10b) was also
(栗,卜Birch还原的产物和竞争速率研究吨OH,NH 3的一系列脂环族化合物中的),(6) - (13),中描述。将烃类(6a)-(8a)和顺甲氧基衍生物(6c)缓慢还原,得到未共轭的二烯,例如(16a)。相反,合成醇(6b)–(8b)迅速还原,分别得到单烯(17),(19)和(22)。减少合成醇(10b)也非常快,但降冰片醇(11a)和(12a)的速率仅显示中等程度的提高。上述每种醇显示出分子内OH⋯键。(1),(6a),(10a),(11b)和(12b)的桦木还原均不符合分子内OHπ键,它们似乎服从三阶动力学[方程式(3)],而与OHπ键结合的醇(6b),(10b),(11a)和(12a)遵循二阶和三阶动力学[方程式(5)]的组合。减少酒精的速率和产品数据(6b)-(8b),(10b),(11a)和(12a)是根据这些基板中分子内OH⋯π键的存在来解释的。观察到的二阶动力学用阴离子自