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• 459-57-4 4-fluorobenzaldehyde 
• 78-94-4 methyl vinyl ketone 
• 579-39-5 1,2-bis(4-fluorophenyl)ethane-1,2-dione 
• 456-22-4 4-Fluorobenzoic acid 
• 1507365-50-5 C₁₇H₁₆F₂O₂ 
• 53458-16-5 1,2-bis(4-fluorophenyl)-2-hydroxyethan-1-one 

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• 929219-25-0 4,5-bis(4-fluorophenyl)-2-[4-(3-chloropropoxy)phenyl]-1,3-dioxolane 

Relevant academic research and scientific papers

Chiral Benzoins via Asymmetric Transfer Hemihydrogenation of Benzils: The Detail that Matters

The synthesis of enantiomerically pure benzoins by hydrogenation of readily available benzils has been long thwarted by their base-sensitivity. We show here that an iron(II) hydride complex catalyzes the asymmetric transfer hydrogenation of benzils from 2-propanol. When strictly base-free conditions are granted, excellent enantioselectivity is achieved even with o-substituted substrates, which are particularly challenging to prepare with other methods. Hence, under optimized reaction conditions, chiral benzoins were prepared in good yields (up to 83%) and excellent enantioselectivity (up to 98% ee) in short reaction times (30-75 min). Also, this work confirms that both enantiomers of the benzoin products can be accessed when a metal catalyst is used, which is a clear advantage over enzymatic methods.

Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst

The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.

CBZ6 as a Recyclable Organic Photoreductant for Pinacol Coupling

A recyclable organic photoreductant (1 mol % CBZ6)-catalyzed reductive (pinacol) coupling of aldehydes, ketones, and imines has been developed. Irradiated by purple light (407 nm) using triethylamine as an electron donor, a variety of 1,2-diols and 1,2-diamines could be prepared. The oxidation potential of the excited state of CBZ6 is established as -1.92 V (vs saturated calomel electrode (SCE)). The relative high reductive potential enables the reductive coupling of carbonyl compounds and their derivatives. CBZ6 can be prepared in gram scale and is acid/base- or air-stable. It could be applied in large-scale photoreductive synthesis and recovered in high yield after the reaction.

Facile pinacol coupling of aliphatic ketones by Brook rearrangement in the presence of samarium species

Herein we report a practical pinacol coupling reaction, in which ketones (aldehydes) react smoothly with Sm and TMSBr to afford the diol products with Sm(II) or (III) siliyl species generated in situ. This reported method affords poor yields for aromatic ketone substrates and good yields for aliphatic ketones. Therefore, it distinguishes from most reductive coupling approaches that are more effective for aromatic carbonyl compounds and provides a facile and robust approach for the pinacol coupling of aliphatic ketones. Mechanistic studies also indicated the pinacolization probably proceeded via an anionic instead of radical coupling pathway involving the Brook rearrangement in the presence of samarium (II or III) silyl species.

Crystal-to-Crystal Synthesis of Photocatalytic Metal–Organic Frameworks for Visible-Light Reductive Coupling and Mechanistic Investigations

Postmodification of reticular materials with well-defined catalysts is an appealing approach to produce new catalytic functional materials with improved stability and recyclability, but also to study catalysis in confined spaces. A promising strategy to this end is the postfunctionalization of crystalline and robust metal–organic frameworks (MOFs) to exploit the potential of crystal-to-crystal transformations for further characterization of the catalysts. In this regard, two new photocatalytic materials, MOF-520-PC1 and MOF-520-PC2, are straightforwardly obtained by the postfunctionalization of MOF-520 with perylene-3-carboxylic acid (PC1) and perylene-3-butyric acid (PC2). The single crystal-to-crystal transformation yielded the X-ray diffraction structure of catalytic MOF-520-PC2. The well-defined disposition of the perylenes inside the MOF served as suitable model systems to gain insights into the photophysical properties and mechanism by combining steady-state, time-resolved, and transient absorption spectroscopy. The resulting materials are active organophotoredox catalysts in the reductive dimerization of aromatic aldehydes, benzophenones, and imines under mild reaction conditions. Moreover, MOF-520-PC2 can be applied for synthesizing gram-scale quantities of products in continuous-flow conditions under steady-state light irradiation. This work provides an alternative approach for the construction of well-defined, metal-free, MOF-based catalysts.

Application of coumarin dyes for organic photoredox catalysis

Here we report the application of readily prepared and available coumarin dyes for photoredox catalysis, 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 could be varied, a wide applicability to several classes of photoredox reactions is predicted.

MeOH or H2O as efficient additive to switch the reactivity of allylSmBr towards carbonyl compounds

A variety of carbonyl compounds were treated by allylSmBr (allylSmBr) with MeOH as the cosolvent to have further insights on the previously reported reductive coupling of aryl ketones mediated by Sm/alkyl halide/MeOH. The results demonstrate that the real reducing species in Sm/alkyl halide/MeOH system should be allylSmBr, and MeOH has elegantly switched the reactivity of allylSmBr from being nucleophilic to being good reductive coupling reagent. Besides, H2O was also found to be a useful additive to realize the pinacol coupling of aliphatic aldehydes and ketones promoted by allylSmBr.

Metal-free reductive coupling of CO and CN bonds driven by visible light: Use of perylene as a simple photoredox catalyst

Perylene, a simple polycyclic aromatic hydrocarbon, was used as a photoredox catalyst to enable the reductive coupling reaction of aromatic aldehydes, ketones, and an imine under visible-light irradiation using a white LED.

An imidazolium-modified chiral rhodium/diamine-functionalized periodic mesoporous organosilica for asymmetric transfer hydrogenation of α-haloketones and benzils in aqueous medium

The use of a hydrophobic, imidazolium-functionalized periodic mesoporous organosilica for immobilization of chiral organometallic complexes as a heterogeneous catalyst is highly desirable as this catalyst can greatly promote an aqueous organic transformation due to its hydrophobic function and phase-transfer feature in an aqueous medium. Herein, by utilizing a three-component co-condensation strategy, we conveniently incorporate 1,2-bis(triethoxysilyl)ethane, (R,R)-4-((trimethoxysilyl)ethyl)phenylsulfonyl-1,2-diphenylethylene-diamine and 1,3-bis(3-(triethoxysilyl)propyl)-1H-imidazol-3-ium iodide within its silicate network, which is coordinated with (Cp?RhCl2)2, leading to an imidazolium-modified chiral rhodium/diamine-functionalized periodic mesoporous organosilica. A solid-state carbon spectrum discloses its well-defined chiral rhodium/diamine active species, and its X-ray diffraction; nitrogen adsorption-desorption measurement and transmission electron microscopy images reveal its ordered dimensional-hexagonal mesostructure. As a bifunctional heterogeneous catalyst, this periodic mesoporous organosilica significantly boosts asymmetric transfer hydrogenation of α-haloketones and benzils in water, where the hydrophobic periodic mesoporous organosilica, phase-transfer-featured imidazolium-functionality, and the confined chiral organorhodium catalytic nature are responsible for its catalytic performance. Furthermore, the catalyst can be recovered and recycled seven times without the loss of its catalytic activity, making it an attractive heterogeneous catalyst for asymmetric transfer hydrogenation in an environmentally friendly manner.

Selective Pinacol Coupling on Regeneratable Supported Acids in Sole Water

Efficient pinacol coupling was developed in sole water, using a reusable heterogeneous supported acid source and zinc as cheap available metal source. This medium can be easily regenerated up to 10-fold without loss of activity. Moreover, supported acids enhance the selectivity of the pinacol coupling reaction compared with homogeneous acids.