Application of coumarin dyes for organic photoredox catalysis
作者:Andrea Gualandi、Giacomo Rodeghiero、Emanuele Della Rocca、Francesco Bertoni、Marianna Marchini、Rossana Perciaccante、Thomas Paul Jansen、Paola Ceroni、Pier Giorgio Cozzi
DOI:10.1039/c8cc04048f
日期:——
Here we report the application of readily prepared and available coumarin dyes for photoredoxcatalysis, which are able to mimic powerful reductant [Ir(III)] complexes. Coumarin derivatives 9 and 10 were employed as photoreductants in pinacol coupling and in other reactions, in the presence of Et3N as a sacrificial reducing agent. As the electronic, photophysical, and steric properties of coumarins
Ti(O-i-Pr)4/Me3SiCl/Mg reagent mediated McMurry coupling of aryl aldehydes to biaryl olefins at near room temperature. This low valent titanium (LVT) reagent also mediated the coupling of aldimines to 1,2-diamines (imino pinacol coupling).
Ti(O - Pr)4 / Me 3 SiCl / Mg试剂在接近室温的条件下介导的芳基醛与联芳基烯烃的McMurry偶联。这种低价钛(LVT)试剂还介导了亚胺与1,2-二胺的偶联(亚氨基频哪醇偶联)。
Photocatalytic Barbier reaction – visible-light induced allylation and benzylation of aldehydes and ketones
作者:Anna Lucia Berger、Karsten Donabauer、Burkhard König
DOI:10.1039/c8sc02038h
日期:——
We report a photocatalytic version of the Barbier type reaction using readily available allyl or benzyl bromides and aromatic aldehydes or ketones as starting materials to generate allylic or benzylic alcohols. The reaction proceeds at room temperature under visible light irradiation with the organic dye 3,7-di(4-biphenyl)1-naphthalene-10-phenoxazine as a photocatalyst and DIPEA as sacrificial electron
Bifunctional Copper-Based Photocatalyst for Reductive Pinacol-Type Couplings
作者:Antoine Caron、Émilie Morin、Shawn K. Collins
DOI:10.1021/acscatal.9b01718
日期:2019.10.4
A bifunctional copper-based photocatalyst has been prepared that employs a pyrazole-pyridine ligand incorporating a sulfonamide moiety that functions as an intramolecular hydrogen-bond donor for a photochemical PCET process. In typical reductive PCET processes, the photocatalyst and H-bond donor must have an appropriate redox potential and pKa, respectively, to promote the PCET. When working in concert
已经制备了双功能铜基光催化剂,其使用掺入磺酰胺部分的吡唑-吡啶配体,该磺酰胺部分用作光化学PCET工艺的分子内氢键供体。在典型的还原性PCET工艺中,光催化剂和H键供体必须分别具有适当的氧化还原电势和p K a,以促进PCET。当在双功能催化剂(例如Cu(pypzs)(BINAP)BF 4)中协同工作时,p K a氢键供体的一半酸度可以降低几个数量级,并且仍然可以有效地促进PCET过程。可以使用贱金属衍生的光催化剂进行频哪醇还原型偶联,以从易得的醛和酮中获得有价值的二醇(24个实例,收率46-99%)。
A Convenient Synthesis of Unsymmetrical Pinacols by Coupling of Structurally Similar Aromatic Aldehydes Mediated by Low-Valent Titanium
pinacol-type couplings between two structurally similar aromatic aldehydes promoted by low-valenttitanium generated unsymmetrical pinacols in moderate to good isolated yields in an erythro/threo ratio of up to 91:9. This synthetic methodology significantly extends the scope of the cross pinacol-type couplings. pinacol - pinacol-type coupling - cross coupling - McMurry coupling - low-valenttitanium