C=C双键与分子氧的氧化裂解产生羰基化合物是化学和药物合成中的一个重要转化。在自然界中,含有第一排过渡金属的酶,特别是血红素和非血红素铁依赖性酶,在环境条件下很容易激活 O 2并以极其精确的方式氧化裂解 C=C 键。然而,该反应对合成化学家来说仍然具有挑战性。只有少数已知的合成金属催化剂允许在 O 2大气压下氧化裂解烯烃,很少有人知道催化未活化烯烃的裂解。在这项工作中,我们描述了一种光驱动、Mn 催化的协议,用于在 1 个大气压的 O 2下将烯烃选择性氧化为羰基化合物。首次使用第一排生物相关金属催化剂,在清洁、温和的条件下,可以将芳香族和各种未活化的脂肪族烯烃氧化成酮和醛。此外,该协议显示出非常好的功能组耐受性。机理研究表明,Mn-oxo 物种,包括不对称的混合价双 (μ-oxo)-Mn(III,IV) 络合物,参与氧化,溶剂甲醇参与 O 2活化,导致oxo 物种的形成。
The first example of the thiyl radical promoted ligand-free iron-catalyzed oxidative cleavage of alkenes using molecular oxygen (1 atm) has been developed. The reaction proceeds under mild reaction conditions with high efficiency and high chemo- and regioselectivity. It features a broad substrate scope and excellent functional group compatibility, enabling facile access to valuable molecules for application
A metal-free heterogeneous photocatalyst for the selective oxidative cleavage of CC bonds in aryl olefins <i>via</i> harvesting direct solar energy
作者:Yu Zhang、Nareh Hatami、Niklas Simon Lange、Emanuel Ronge、Waldemar Schilling、Christian Jooss、Shoubhik Das
DOI:10.1039/d0gc01187h
日期:——
transition metal-free) to avoid further leaching in the final products. This is for sure a big challenge to an organic chemist and to the pharmaceutical industries! To make this feasible, a mild and efficient protocol has been developed using polymericcarbonnitrides (PCN) as metal-free heterogeneous photocatalysts to convert various olefins into the corresponding carbonyls. Later, this catalyst has been
C C键的选择性裂解对于合成含羰基的精细化学品和药物非常重要。新型方法,例如臭氧分解反应,Lemieux-Johnson氧化反应等。已经存在。与此平行,还发现了使用均相催化剂的催化方法。考虑到非均相催化剂的各种优点,例如可循环性和稳定性,已将几种基于过渡金属的非均相催化剂用于该反应。但是,制药行业更喜欢使用不含金属的催化剂(尤其是不含过渡金属的催化剂),以避免最终产品中进一步浸出。对于有机化学家和制药行业来说,这无疑是一个巨大的挑战!为了使之可行,已经开发了一种温和而有效的方案,使用聚合碳氮化物(PCN)作为无金属的非均相光催化剂,将各种烯烃转化为相应的羰基。后来,该催化剂已被用于使用直接太阳能的克级合成药物中。详细的机械研究揭示了氧气,催化剂和光源的实际作用。
Catalytic Carbocation Generation Enabled by the Mesolytic Cleavage of Alkoxyamine Radical Cations
作者:Qilei Zhu、Emily C. Gentry、Robert R. Knowles
DOI:10.1002/anie.201604619
日期:2016.8.16
weak C−O bond. Spontaneous scission results in the formation of the stable nitroxyl radical TEMPO. as well as a reactive carbocation intermediate that can be intercepted by a wide range of nucleophiles. Notably, this process occurs underneutralconditions and at comparatively mild potentials, enabling catalytic cation generation in the presence of both acid sensitive and easily oxidized nucleophilic
Photoinduced [3+2] Annulation of Alkene with o-Iodoanilines: An Expedient Approach to Indolines
作者:Wujiong Xia、Xinxin Zhao、Lin Guo、Chao Yang
DOI:10.1055/s-0040-1705963
日期:2021.4
A highly regioselective [3+2] cyclization of alkenes with 2-iodoanilines under the irradiation of UV light is described. This general, metal-free strategy facilitates the direct preparation of 2-mono-/disubstituted indolines as well as spiroindolines through alkene carboamination in one step. Mechanistic studies suggested that the photochemical protocol proceeded via a radical pathway.
Continuous Flow Ozonolysis in a Laboratory Scale Reactor
作者:Muhammad Irfan、Toma N. Glasnov、C. Oliver Kappe
DOI:10.1021/ol102984h
日期:2011.3.4
Several important types of ozonolysis reactions have been performed in a continuous flow device that is able to perform both the ozonolysis and quenching steps in flow mode. This technique allows safe and scalable ozonolysis reactions to be performed on a laboratoryscale.