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。
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。
Alkynylphenyl-substituted 1,3-oxathione compounds with pesticidal
申请人:The Regents of the University of California
公开号:US05061726A1
公开(公告)日:1991-10-29
Pesticidally-active alkynylphenyl-substituted 1,3-oxathianes and related substituted compounds of the formula: ##STR1## and their use in controlling pests such as arthropods and helminths are described.
Conformationally constrained 2-methylidene 1,3-oxathiane S-oxides: synthesis and nucleophilic additions
作者:Daniel Weingand、Claude Kiefer、Joachim Podlech
DOI:10.1016/j.tet.2014.12.098
日期:2015.2
substrates were prepared by oxidation of 2-hydroxymethyl-1,3-oxathianes and pyrolysis of the respective xanthogenates. Nucleophilic additions of ethyl thiolate, piperidine, and dimethyl malonate anion are over 100 times faster to axial sulfoxides than to the respective equatorial substrates. The oxathiane derivatives turned out to be about 1000 times less reactive than the respective 1,3-dithianes.
1,3-Oxathianes with suitable 2- and and 5-substituents are highly potent insecticides. In some cases 1,3-oxathiane 3-oxides and 1,3-oxathiane 3,3-dioxides derived by m-chloroperoxybenzoic acid oxidation of the 1,3-oxathianes are even more effective. Housefly LD(50)s for trans-5(e)-tert-butyl-2(e)-(4-ethynylphenyl)-1,3-oxathiane 3,3-dioxide are 0.3 and 0.03 mu g/g alone and with piperonyl butoxide respectively. It is the most insecticidal analogue in the oxathiane series and approaches the potency of (1R)-cis-permethrin.