Sterically Hindered Chelating Alkyl Phosphines Provide Large Rate Accelerations in Palladium-Catalyzed Amination of Aryl Iodides, Bromides, and Chlorides, and the First Amination of Aryl Tosylates
作者:Chingakham B. Singh、Veerababurao Kavala、Akshaya K. Samal、Bhisma K. Patel
DOI:10.1002/ejoc.200600937
日期:2007.3
Direct N-alkylation of primary amines to secondary/tertiary amines and of secondary amines to tertiary amines has been achieved in excellent yields by employing alkyl, benzylic and allylic halides in the presence of NaHCO3 in an aqueous medium at an elevated temperature. Amines of different stereoelectronic nature react with ease with different halides. The selective formation of secondary amines and
Bulky diadamantyl aryl phoshine ligands were synthesized and utilized in Buchwald‐Hartwig couplingreactions of sterically demanding ortho‐substituted arylchlorides. The ligands also showed enhanced catalytic activity in the coupling of tosyl hydrazones and aryl halides.
the coupling of electron-rich and electron-poor aryl halides with both primary and secondary alkyl amines. In this study, it is reported that a Ni(II)-bipyridine complex catalyzes efficient C–N coupling of aryl chlorides and bromides with various primary and secondary alkyl amines under direct excitation with light. Intramolecular C–N coupling is also demonstrated. The feasibility and applicability of
Hydrazine der Formel
worin
R einen Aryl- oder Aralkylrest und
R einen Alkyl-, Aryl- oder Aralkylrest bedeuten, oder wenn R für einen Arylrest steht,
R1 auch für einen Alkylen- oder Cycloalkylenrest stehen kann, der mit R in der ortho-Stellung zum Stickstoff verbunden ist, werden hergestellt, indem man sekundäre Amine der Formel
zu Nitrosaminen umsetzt und diese ohne Isolierung bei 0 bis 50° C und bei pH-Werten von 5 bis 6 mit Zinkstaub in Gegenwart von Salzsäure oder Schwefelsäure reduziert und die Reduktion bei pH-Werten von unter 4 zu Ende führt.
式中 R 为芳基或芳烷基,R 为烷基、芳基或芳烷基,或者如果 R 为芳基,R1 也可以是亚烷基或环亚烷基,该亚烷基或环亚烷基在氮的正交位置上与 R 连接,制备方法是将式中的仲胺与亚硝胺反应,然后在 0 至 50℃、pH 值为 5 至 6 的条件下,在盐酸或硫酸存在下用锌粉不经分离地还原这些亚硝胺,并在 pH 值低于 4 的条件下完成还原。
Use of Primary Amines for the Selective N-Alkylation of Anilines by a Reusable Heterogeneous Catalyst
Traditionally, anilines can be alkylated with reactive alkyl halides but now more safe reagents such as alcohols or even amines can be used. To overcome the limits of homogeneous catalysis for aniline N-alkylation, we have developed a protocol that employs simple Pd/C as a heterogeneous catalyst under microwave dielectric heating. The process, based on the easy Pd-mediated oxidation of primary amines to imines followed by aniline addition, is characterized by a high atom economy as ammonia is the only other product of the reaction. This kind of aniline alkylation with amines has been carried out both in ionic liquid medium using [bmim]PF6 or in a more traditional solvent such as THF where the catalyst could be successfully recycled more times. The reusability of the catalyst was further confirmed by using material recycled from the amination in a standard alkene hydrogenation without loss of efficiency.