The influence of anchoring substitution in 1,3-amino alcohols on the rate and mechanism of esterification by acetylimidazole and by p-nitrophenyl acetate
通过常规方法制备了3-(二甲基氨基)丙-1-醇和七个在2-位具有烷基取代基的衍生物,并在拟第一个条件下测定了N-乙酰基咪唑在乙腈中酯化的二阶速率常数。在单一温度(23°C)下通过1 H NMR光谱法和在25–65°C的温度范围内通过UV光谱法测定有序条件。证据表明,分子间酯化反应是通过确定分子速率的分子内一般碱催化环状四面体中间体的形成而进行的。与简单醇与三乙胺催化的乙酰咪唑的三阶反应相比,有效摩尔数估计为13–14 mol dm–3,但氨基醇2位上的烷基取代对反应速率的影响很小。所有反应均具有基本负的活化熵,并且只有适度的活化焓,这是具有高度有序过渡结构的协同双分子反应所期望的。三种结构相关的碳环氨基醇组成一个短的等速序列,其等速温度非常接近实验范围。在这个系列中,越来越少的激活熵对激活焓降低了几乎完全平衡,它们对室温附近的总激活自由能的贡献。
Some new alkamino esters of quinuclidine-, piperidine- and pyridinecarboxylic acids
作者:E. S. Nikitskaya、E. I. Levkoeva、V. S. Usovskaya、M. V. Rubtsov
DOI:10.1007/bf00768577
日期:1967.3
Some new alkamino esters of quinuclidine-2-carboxylic, 1,6-dimethylpiperidine-2-carboxylic and 6-methylpyridine-2-carboxylic acid and their quaternary salts have been synthesized for pharmacological study. The methods of synthesis for some alkamino alcohols are described.
Structure–reactivity relationships in the rate of esterification by acetylimidazole: the influence of the second hydroxy group and of the length of the N-ω-hydroxy-n-alkyl chain in 3-(N-methyl, N-ω-hydroxy-n-alkyl)amino-2- tert-butylpropan-1-ols
作者:Annemieke Madder、Pierre J. De Clercq、Howard Maskill
DOI:10.1039/a608033b
日期:——
Enforced intramolecular hydrogen bonding facilitates
intramolecular general base catalysis in the acetylation of a family of
α,Ï-amino alcohols by acetylimidazole, and the site of
acetylation when there are two hydroxy groups is determined by the
relative ease of intramolecular hydrogen bonding rather than by
intermolecular steric effects.
Stepwise Approach toward First Generation Nonenzymatic Hydrolases
作者:Annemieke Madder、Pierre J. De Clercq、Jean-Paul Declercq
DOI:10.1021/jo971935+
日期:1998.4.1
The synthesis and reactivity study of a first generation serine protease mimic is described. Central in the design stands the possibility of stabilization of the transition state by an amino triol such as 8t. En route to 8t, a series of amino alcohols (4-8) was obtained, the reactivity of which was studied toward esterification by acetylimidazole (AcIm) and by p-nitro-2,2,2-trifluoroacetanilide (PNTFA). Interesting reactivity differences were observed between the cis-and the trans-series, especially between 7c and 7t (AcIm), and between 8c and 8t (PNTFA). In both cases the results are explained by invoking extra stabilization of the tetrahedral oxyanion.
US7160907B2
申请人:——
公开号:US7160907B2
公开(公告)日:2007-01-09
Mechanism of esterification of 1,3-dimethylamino alcohols by N-acetylimidazole in acetonitrile and the influence of alkyl and geminal dialkyl substitution upon the rate
作者:Annemieke Madder、Sonny Sebastian、Dirk Van Haver、Pierre J. De Clercq、Howard Maskill
DOI:10.1039/a608488e
日期:——
catalysed formation of a cyclic tetrahedral intermediate. Effective molarities compared with the third-order reactions of simpler alcohols with acetylimidazole catalysed by triethylamine are estimated to be 13–14 mol dm–3, but alkyl substitution at the 2-position of the aminoalcohol has only a modest effect upon reaction rates. All reactions have substantial negative entropies of activation and only modest
通过常规方法制备了3-(二甲基氨基)丙-1-醇和七个在2-位具有烷基取代基的衍生物,并在拟第一个条件下测定了N-乙酰基咪唑在乙腈中酯化的二阶速率常数。在单一温度(23°C)下通过1 H NMR光谱法和在25–65°C的温度范围内通过UV光谱法测定有序条件。证据表明,分子间酯化反应是通过确定分子速率的分子内一般碱催化环状四面体中间体的形成而进行的。与简单醇与三乙胺催化的乙酰咪唑的三阶反应相比,有效摩尔数估计为13–14 mol dm–3,但氨基醇2位上的烷基取代对反应速率的影响很小。所有反应均具有基本负的活化熵,并且只有适度的活化焓,这是具有高度有序过渡结构的协同双分子反应所期望的。三种结构相关的碳环氨基醇组成一个短的等速序列,其等速温度非常接近实验范围。在这个系列中,越来越少的激活熵对激活焓降低了几乎完全平衡,它们对室温附近的总激活自由能的贡献。