63163-08-6Relevant articles and documents
Using Data Science To Guide Aryl Bromide Substrate Scope Analysis in a Ni/Photoredox-Catalyzed Cross-Coupling with Acetals as Alcohol-Derived Radical Sources
Doyle, Abigail G.,Gandhi, Shivaani S.,Jiang, Shutian,Kariofillis, Stavros K.,Martinez Alvarado, Jesus I.,?urański, Andrzej M.
supporting information, p. 1045 - 1055 (2022/01/19)
Ni/photoredox catalysis has emerged as a powerful platform for C(sp2)–C(sp3) bond formation. While many of these methods typically employ aryl bromides as the C(sp2) coupling partner, a variety of aliphatic radical sources have been investigated. In principle, these reactions enable access to the same product scaffolds, but it can be hard to discern which method to employ because nonstandardized sets of aryl bromides are used in scope evaluation. Herein, we report a Ni/photoredox-catalyzed (deutero)methylation and alkylation of aryl halides where benzaldehyde di(alkyl) acetals serve as alcohol-derived radical sources. Reaction development, mechanistic studies, and late-stage derivatization of a biologically relevant aryl chloride, fenofibrate, are presented. Then, we describe the integration of data science techniques, including DFT featurization, dimensionality reduction, and hierarchical clustering, to delineate a diverse and succinct collection of aryl bromides that is representative of the chemical space of the substrate class. By superimposing scope examples from published Ni/photoredox methods on this same chemical space, we identify areas of sparse coverage and high versus low average yields, enabling comparisons between prior art and this new method. Additionally, we demonstrate that the systematically selected scope of aryl bromides can be used to quantify population-wide reactivity trends and reveal sources of possible functional group incompatibility with supervised machine learning.
PHANE-TetraPHOS, the First D2 Symmetric Chiral Tetraphosphane. Synthesis, Metal Complexation, and Application in Homogeneous Stereoselective Hydrogenation
Benincori, Tiziana,Cirilli, Roberto,Pierini, Marco,Rizzo, Simona,Terraneo, Giancarlo,Vaghi, Luca
, p. 2367 - 2374 (2021/06/25)
PHANE-TetraPHOS, a new D2 symmetric tetraphosphane based on the [2.2]paracyclophane scaffold, has been synthesized and characterized. The peculiarity of this system is the presence of four homotopic diphenylphosphane groups, exchangeable through C2 symmetry operations and consequently indistinguishable. Their spatial arrangement allows the simultaneous complexation of two metal atoms. Enantiomeric purity was attained at tetra-phosphane oxide level by fractional crystallization of the diastereomeric adducts obtained from the racemate with enantiopure dibenzoyltartaric acids. Alkaline treatment of diastereomerically pure adducts followed by exhaustive P?O groups reduction with HSiCl3 gave both PHANE-TetraPHOS antipodes in an enantiopure state. They were tested as rhodium ligands in the homogeneous enantioselective hydrogenation of some benchmark unsaturated compounds. Catalytic activity and enantiodiscrimination ability were found comparable to those exhibited by the complexes of the parent bidentate ligand PHANEPHOS, but only half a mole of precious chiral ligand was employed.
Generation of Functionalized Alkyl Radicals via the Direct Photoexcitation of 2,2′-(Pyridine-2,6-diyl)diphenol-Based Borates
Miyamoto, Yusuke,Sumida, Yuto,Ohmiya, Hirohisa
supporting information, p. 5865 - 5870 (2021/07/31)
A new type of alkylborate was developed for the purpose of generating radicals via direct photoexcitation. These borates were prepared using 2,2′-(pyridine-2,6-diyl)diphenol as a tridentate ligand together with organoboronic acids or potassium trifluoroborates. The ready availability of organoboron compounds is a significant advantage of this direct photoexcitation protocol. The excited states of these borates can also serve as strong reductants, enabling various transformations.
