有机卤化物的催化羰基化是化学合成中重要的 CC 键形成。未活化烷基卤化物的羰基化仍然是一个挑战,目前需要在苛刻条件和高压 CO 下使用烷基碘。在此我们报告了钯催化的仲烷基溴烷氧基羰基化,在温和条件下在低压 (2 atm CO) 下进行. 初步机理研究与混合有机金属-自由基过程一致。这些反应有效地将未活化烷基溴的酯传递到各种底物上,并代表了烷基溴与一氧化碳的第一次催化羰基化。
Design of a Photoredox Catalyst that Enables the Direct Synthesis of Carbamate-Protected Primary Amines via Photoinduced, Copper-Catalyzed <i>N</i>-Alkylation Reactions of Unactivated Secondary Halides
作者:Jun Myun Ahn、Jonas C. Peters、Gregory C. Fu
DOI:10.1021/jacs.7b10907
日期:2017.12.13
carbamates with unactivated secondary alkyl bromides at room temperature. Our mechanistic observations are consistent with the newcoppercomplex serving its intended role as a photoredox catalyst, working in conjunction with a second coppercomplex that mediates C-N bond formation in an out-of-cage process.
尽管氮亲核试剂和烷基亲电试剂之间的 SN2 反应历史悠久,但许多此类取代反应仍然遥不可及。近年来,开发过渡金属催化剂以解决这一缺陷的努力已经开始出现。在本报告中,我们解决了将氨基甲酸酯亲核试剂与未活化的仲烷基亲电试剂偶联以生成取代氨基甲酸酯的挑战,这一过程在没有催化剂的情况下无法有效实现;氨基甲酸酯产品本身可用作有机合成中的有用中间体以及生物活性化合物。通过设计和合成一种新的铜基光氧化还原催化剂,带有三齿咔唑/双膦配体,可以在蓝光 LED 灯照射下激活,我们可以在室温下实现一系列伯氨基甲酸酯与未活化的仲烷基溴的偶联。我们的机械观察结果与新的铜配合物作为光氧化还原催化剂的预期作用一致,与第二种铜配合物协同工作,后者在笼外过程中介导 CN 键的形成。
Absolute Rate Expressions for Hydrogen Atom Abstraction from Molybdenum Hydrides by Carbon-Centered Radicals
作者:James A. Franz、John C. Linehan、Jerome C. Birnbaum、Kenneth W. Hicks、M. S. Alnajjar
DOI:10.1021/ja991412e
日期:1999.10.1
expressions for hydrogenatomabstraction by primary, secondary, and tertiary alkyl radicals in dodecane and benzyl radical in benzene from the molybdenum hydride Cp*Mo(CO)3H and for reactions of a primary alkyl radical with CpMo(CO)3H in dodecane are reported (Cp* = η5-pentamethylcyclopentadienyl, Cp = η5-cyclopentadienyl). Rate expressions for reaction of primary, secondary, and tertiary radical clocks with
It has been demonstrated by means of spectroscopic studies involving cyclizable alkyl halides that lithium dimethylcuprate can react with organichalides by a single electron transfer pathway.
Evidence for single electron transfer in metal-halogen exchange. The reaction of organolithium compounds with alkyl halides.
作者:E.C. Ashby、Tung N. Pham、Bongjin Park
DOI:10.1016/s0040-4039(00)94925-6
日期:1985.1
The reaction of t-BuLi with cyclizable 1° and 2° alkyl halide radical probes at low temperature produced stab]e cyclized and uncyclized organolithium products as well as cyclized hydrocarbons which clearly indicate the presence of radical intermediates during the course of these reactions.
Photoinduced, Copper-Catalyzed Alkylation of Amines: A Mechanistic Study of the Cross-Coupling of Carbazole with Alkyl Bromides
作者:Jun Myun Ahn、Tanvi S. Ratani、Kareem I. Hannoun、Gregory C. Fu、Jonas C. Peters
DOI:10.1021/jacs.7b07052
日期:2017.9.13
pathway proceeds from the excited state of Li(carb), generating a carbazyl radical and an alkyl radical. The cross-coupling of these radicals is catalyzed by copper via an out-of-cage mechanism in which [CuI(carb)2]- and [CuII(carb)3]- (carb = carbazolide), both of which have been identified under coupling conditions, are key intermediates, and [CuII(carb)3]- serves as the persistent radical that is responsible