Aggregation and Reactivity of the Cesium Enolate of 6-Phenyl-α-tetralone: Comparison with the Lithium Enolate<sup>1</sup>
作者:Daniel Zerong Wang、Andrew Streitwieser
DOI:10.1021/jo034543d
日期:2003.11.1
For comparison, the lithium enolate, LiPAT, is also a monomer-tetramer with K(1,4) = 4.7 x 10(10) M(-3) and a monomer pK = 14.22. HMPA in large amounts promotes dissociation to monomer with both enolates. Ion-pair S(N)2 initial rates were measured for CsPAT with several alkyl halides and with methyl tosylate and compared with other rates with LiPAT. In all cases, the enolate monomers are much more reactive
6-苯基-α-四氢萘酮的铯烯醇铯(CsPAT)在387 nm处的THF中具有λ(最大值),但是浓度的变化对于应用奇异值分解而言太小了。具有几个指标的质子转移研究表明,CsPAT形成具有四聚化平衡常数K(1,4)= 2.3 x 10(11)M(-3)的单体-四聚体混合物。单体的pK为23.39,其中芴分配为22.9(每氢)。为了进行比较,烯醇锂LiPAT也是K-(1,4)= 4.7 x 10(10)M(-3)和pK = 14.22的单体四聚体。大量的HMPA促进与两种烯醇化物的离解。使用几种烷基卤化物和甲苯磺酸甲酯测量CsPAT的离子对S(N)2初始速率,并将其与LiPAT的其他速率进行比较。在所有情况下,烯醇盐单体比聚集体具有更高的反应性。CsPAT与烷基卤的反应通常是C-烷基化,但是HMPA促进O-烷基化的增加。一种新的指示剂,11-甲基-11H-苯并[b]芴,在铯尺度上的pK为23.39。