Stereoselective Three-Component Allylic Alkylation Enabled by Dual Photoredox/Ni Catalysis
作者:Qian Zeng、Fengyun Gao、Jordi Benet-Buchholz、Arjan W. Kleij
DOI:10.1021/acscatal.3c01686
日期:2023.6.2
modular and practical approach has been developed for the stereoselective formation of elaborate allylic alcohols through a three-component reaction (3CR) between vinyl cyclic carbonates, olefins, and various radical precursors using dual photoredox/Ni catalysis. The developed process expands the potential of radical-based allylicalkylation to multicomponent approaches under high regio- and stereocontrol
Modular construction of <i>N</i>-arylated amino acid esters enabled by a photoredox-catalyzed multicomponent reaction
作者:Qing Li、Hanhan Sun、Fengying Yan、Yuanyuan Zhao、Yicheng Zhang、Chao Zhou、Man-yi Han、Hongji Li、Xianwei Sui
DOI:10.1039/d3gc01633a
日期:——
An efficient photoredox-catalyzed three-component coupling reaction of aryl amine, glyoxalate and alkyltrifluoroborates has been reported. A variety of N-arylated aminoesters were constructed rapidly using an organic photocatalyst under mild conditions. Broad substrate scope and good functional group tolerance are the key features of this strategy.
Novel tetraalkyltetraboranes of the type B4R4, B4H2R4 and B4H4R4
作者:Andreas Neu、Theo Mennekes、Peter Paetzold、Ulli Englert、Matthias Hofmann、Paul von Ragué Schleyer
DOI:10.1016/s0020-1693(99)00058-4
日期:1999.6
The reduction of RBHal(2) (Hal = F, Cl, Br) with Na/K alloy gives the tetraboranes B4R4, B4H2R4 or their mixtures, depending on temperature, reaction time and solvent. We describe here (B4Bu4)-Bu-t, B-4((CH2Bu)-Bu-t)(4) (B4H2Bu4)-Bu-t, B4H2((CH2Bu)-Bu-t)(4) and B4H2(CMe2Et)(4). (B4Bu2)-Bu-t((CH2Bu)-Bu-t)(2) is formed by reducing the diborane Cl-B(Bu-t)-B((CH2Bu)-Bu-t)-Cl with Li. The conversion of (B4H2Bu4)-Bu-t into (B4H4Bu4)-Bu-t proceeds in three steps: (i) reduction (-->[(B4H2Bu4)-Bu-t](2-)); (ii)first protonation (-->[(B4H3Bu4)-Bu-t](-)), and (iii) second protonation (-->(B4H4Bu4)-Bu-t). The hypercloso-species B4R4 have: tetrahedral structures. The two opposite edges of a B-4 tetrahedron of the closo-B4H2R4 are bridged by H atoms (D-2d). The nido-species have a bicyclobutane-type B-4 skeleton; three of the four outside edges are bridged by H atoms; two terminal ligands are bound to one of the B atoms: H in exo- and Bu-t in endo-position (C-1). Structural evidence is based on low-temperature NMR spectra, ab initio geometries, and IGLO(DZ) calculations of the B-11 NMR shifts. Dynamical behavior of bridging H atoms is indicated by the NMR spectra at higher temperature. (C) 1999 Elsevier Science S.A. Pill rights reserved.
10.1002/chem.202401774
作者:Ge, Yuhua、Peng, Yijiang、Xie, Ruoqian、Luo, Yang、Li, Yangyan、Chen, Gang
DOI:10.1002/chem.202401774
日期:——
We present herein a novel photo‐mediated homolytic C‐S bond formation for the preparation of alkylthiopurines and alkylthiopurine nucleosides. Despite the presence of reactive sites for the Minisci reaction, chemoselective S‐alkylation remained the predominant pathway. This method allows for the late‐stage introduction of a broad spectrum of alkyl groups onto the sulfur atom of unprotective mercaptopurine derivatives, encompassing 2‐, 6‐, and 8‐mercaptopurine rings. Organoborons serve as efficient and eco‐friendly alkylating reagents, providing advantages in terms of readily availability, stability, and reduced toxicity. Further derivatization of the thioetherified nucleosides, together with anti‐tumor assays, led to the discovery of potent anti‐tumor agents with an IC50 value reaching 6.1 µM (Comp. 31 for Jurkat).
Photoelectrochemical C−H Alkylation of Heteroarenes with Organotrifluoroborates
作者:Hong Yan、Zhong‐Wei Hou、Hai‐Chao Xu
DOI:10.1002/anie.201814488
日期:2019.3.26
A photoelectrochemical method for the C−H alkylation of heteroarenes with organotrifluoroborates has been developed. The merger of electrocatalysis and photoredox catalysis provides a chemical oxidant‐free approach for the generation and functionalization of alkylradicals from organotrifluoroborates. A variety of heteroarenes were functionalized using primary, secondary, and tertiary alkyltrifluoroborates