Reactivity of the Carbocations Stabilized by Divalent Sulfur and Application to Organic Synthesis

二价硫稳定碳正离子的反应活性及其在有机合成中的应用

• 批准号: 60470094
• 负责人: OKUYAMA Tadashi
• 金额: $ 0.38万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60470094/
• 关键词: Carbocation; Ketene dithioacetal; Ortho ester; Photochemical ionization; Flash photolysis; 閃光光分解; 加水分解; 二価硫黄

A new simple method for isolation of sulfur-stabilized carbocations, 1,3-dithiolan-2-ylium and 1,3-dithian-2-ylium ions, as salts was presented, and the isolated salts were converted to ketene dithioacetals and ortho esters. Reactions of the salts with nucleophiles, such as thiols and sulfinates afforded adducts, which were used as precursors for photochemical generation of dithio carbocations.Reactions of the isolated salts in aqueous solution were kinetically examined and a detailed mechanism of the breakdown of the tetrahedral intermediate was presented. Hydrolysis of Mixed O,S-ortho esters also provided useful information on the mechanism of the breakdown of the tetrahedral intermediate.Kinetic investigations on the acid-catalyzed hydrolysis of ketene dithioacetals showed that the dithio carbocation intermediates easily deprotonate; i. e., the protonation is reversible. Effects of an internal hydroxyl group on the hydrolysis of ketene dithioacetal resulted in a discovery of a new mode of anchimeric assistance; an internal solvation mechanism.Flash photolysis was carried out with a xenone lamp on aqueous solutions of 2-(p-toluene-sulfonyl)-1, 3-dithiolane and 2-(p-chlorophenylthio)-1,3-dithiolane, and their 2-phenyl derivatives. UV spectra, rapidly scanned with an MCPD detector, showed that the transient intermediate is dithiolanylium ion. Decay curves of the transient cation were more rapid than those expected for the first-order decay and recombination of the cation and the counter anions formed was considered to contribute to this reaction. In the presence of thiol or sulfinate, the decay of the cation followed the first-order kinetics and the second-order rate constants for the reactions with the nucleophiles were obtained.Further determinations of rate constants for reactions of a variety of nucleophiles and carbocations are planned.

提出了一种新的分离硫稳定碳正离子1，3-二硫戊环-2-烯鎓和1，3-二噻烷-2-烯鎓盐的简单方法，并将分离的盐转化为烯酮二硫代缩醛和原酸酯。盐与亲核试剂如硫醇和亚磺酸盐反应生成加合物，这些加合物可作为光化学生成二硫代碳正离子的前体，对盐在水溶液中的反应进行了动力学研究，并提出了四面体中间体分解的详细机理。混合O，S-原酸酯的水解反应也为四面体中间体的分解机理提供了有用的信息。即，质子化是可逆的。用氙酮灯对2-（对甲苯磺酰基）-1，3-二硫戊环和2-（对氯苯硫基）-1，3-二硫戊环及其2-苯基衍生物的水溶液进行了闪光光解研究。用MCPD检测器快速扫描的紫外光谱表明，瞬态中间体是二硫戊环基二硫代正离子。瞬态阳离子的衰减曲线比预期的一级衰减和重组的阳离子和反阴离子形成被认为有助于这一反应。在硫醇或亚磺酸盐存在下，阳离子的衰变遵循一级动力学，得到了与亲核试剂反应的二级速率常数，并计划进一步测定各种亲核试剂与碳正离子反应的速率常数。

项目成果

Tadashi Okuyama: "Mechanism of Hydrolysis of 1,3-Dithiane Derivatives. Breakdown of the Tetrahedral Intermediate" J. Org. Chem.51. 4988-4990 (1986)

Tadashi Okuyama：“1,3-二噻烷衍生物的水解机制。四面体中间体的分解”J. Org。

奥山格: Can.J.Chem.64. 1116-1123 (1986)

奥山治：Can.J.Chem.64。1116-1123（1986）

奥山格: Bull.Chem.Soc.Japan. 59. 327-328 (1986)

Itaru Okuyama：Bull.Chem.Soc.Japan 59. 327-328 (1986)。

奥山格: J.Am.Chem.Soc.107. 4224-4229 (1985)

奥山治：《J.Am.Chem.Soc.107》4224-4229（1985）

奥山格: Bull.Chem.Soc.Japan. 59. 453-456 (1986)

Itaru Okuyama：Bull.Chem.Soc.Japan 59. 453-456 (1986)。