Sulfonic peracids — III. Heteroatom oxidation and chemoselectivity
作者:R. Kluge、M. Schulz、S. Liebsch
DOI:10.1016/0040-4020(96)00202-5
日期:1996.4
investigated thep-toluenesulfonic peracid (2) generated in situ in the oxidation of different types of compounds containing nitrogen and/or sulfur. The sulfonic peracid2 shows a remarkable chemoselectivity characterized by a preferred oxidation of sulfides to the sulfones in the presence of amines or olefins and a strong dependence on the nature of the amine in the competitive oxidation of olefins and amines.
Nitrones serve as starting materials for the synthesis of many heterocycles. Oxidation of secondary amines using hydrogen peroxide and the catalytic amount of methyltrioxorhenium in ionic liquids is a useful method for the preparation of nitrones. Ultrasonic irradiation and ionic liquids have a positive influence on the reaction. The nitrones required were isolated in good yields. Corresponding hydroxylamines
One-flask transformation of secondary amines to nitrones by oxidation with hydrogen peroxide mediated by triscetylpyridinium tetrakis oxodiperoxotungsto-phosphate (PCWP). Some mechanistic considerations
作者:Francesco P. Ballistreri、Ugo Chiacchio、Antonio Rescifina、Gaetano A. Tomaselli、Rosa M. Toscano
DOI:10.1016/s0040-4020(01)89443-6
日期:——
Acyclic and cyclic secondary amines are oxidized to nitrones by H2O2/PCWP system in water/chloroform under phase transfer catalysis conditions. The different acidities of the protons of the carbon atoms α to the nitrogen might be responsible for the identity and ot the stereochemistry of the formed nitrone. The presence of an aromatic ring such as benzene directly linked to the nitrogen represents
在相转移催化条件下,H 2 O 2 / PCWP体系在水/氯仿中将无环和环状仲胺氧化为硝酮。碳原子α的质子对氮的不同酸度可能是所形成的硝酮的身份和立体化学的原因。直接连接到氮上的芳环如苯的存在是一个限制,因为在这种情况下观察到许多氧化产物。就机械方面而言,建议氧化过程可通过胺对过氧金属配合物的过氧化氧的亲核攻击或从胺到氧化剂的单电子转移而开始。
Selenium dioxide catalyzed oxidation of secondary amines with hydrogen peroxide. Simple synthesis of nitrones from secondary amines
作者:Shun-Ichi Murahashi、Tatsuki Shiota
DOI:10.1016/s0040-4039(00)96130-6
日期:——
Oxidation of secondary amines with hydrogen peroxide in the presence of selenium dioxide catalyst at room temperature gives nitrones, which are versatile synthetic intermediates, highly efficiently.
Efficient Synthesis of Highly Functionalized Indazoles and 2,3-Dihydro-1,2-benzisoxazoles by Reaction of Stable Fischer Dienyl Carbenes and Isocyanides
A range of stable chromium and tungsten Fischer dienyl carbenes have been prepared by [3+2] cycloaddition of alkenylethynyl carbenecomplexes with nitrones or diazoalkanes. Treatment of these systems with isocyanides gives entry to highly functionalized 2,3-dihydro-1,2-benzisoxazoles and indazoles in a completely regioselective fashion, under mild conditions, and with high yields. This methodology