Silver-Catalyzed Decarboxylative Fluorination of Aliphatic Carboxylic Acids in Aqueous Solution

Although fluorinated compounds have found widespread applications in the chemical and materials industries, general and site-specific C­(sp³)–F bond formations are still a challenging task. We report here that with the catalysis of AgNO₃, various aliphatic carboxylic acids undergo efficient decarboxylative fluorination with SELECTFLUOR^® reagent in aqueous solution, leading to the synthesis of the corresponding alkyl fluorides in satisfactory yields under mild conditions. This radical fluorination method is not only efficient and general but also chemoselective and functional-group-compatible, thus making it highly practical in the synthesis of fluorinated molecules. A mechanism involvinig Ag­(III)-mediated single electron transfer followed by fluorine atom transfer is proposed for this catalytic fluorodecarboxylation

Silver-Catalyzed Decarboxylative Alkynylation of Aliphatic Carboxylic Acids in Aqueous Solution

C­(sp³)–C­(sp) bond formations are of immense interest in chemistry and material sciences. We report herein a convenient, radical-mediated and catalytic method for C­(sp³)–C­(sp) cross-coupling. Thus, with AgNO₃ as the catalyst and K₂S₂O₈ as the oxidant, various aliphatic carboxylic acids underwent decarboxylative alkynylation with commercially available ethynylbenziodoxolones in aqueous solution under mild conditions. This site-specific alkynylation is not only general and efficient but also functional group compatible. In addition, it exhibits remarkable chemo- and stereoselectivity

Spindle-Shaped Apatite La–Silicate Mesocrystals Grown via a Multistep Nucleation and Growth Mechanism, A New Strategy for Preparing Ordered Nanoscale Superstructures

A precise control over the growth of mesocrystals composed of crystallographically aligned nanocrystals is necessary to exploit their collective properties for potential applications. Here, we describe a successful preparation of spindle-shaped apatite La–silicate (ap-LSO) mesocrystals with an ordered arrangement of elongated nanocrystals along <i>c</i>-axis through a solvothermal process, as revealed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy–selected area electron diffraction, and high-resolution transmission electron microscopy. It has been shown that a multistep nucleation and growth mechanism would be responsible for the formation of the mesocrystals. This novel mesocrystal formation mechanism breaks through the classical crystallization norm and opens a new way to constructing mesocrystals with nanoscale superstructures

Silver-Catalyzed Radical Phosphonofluorination of Unactivated Alkenes

We report herein a mild and catalytic phosphonofluorination of unactivated alkenes. With catalysis by AgNO₃, the condensation of various unactivated alkenes with diethyl phosphite and Selectfluor reagent in CH₂Cl₂/H₂O/HOAc at 40 °C led to the efficient synthesis of β-fluorinated alkylphosphonates with good stereoselectivity and wide functional group compatibility. A mechanism involving silver-catalyzed oxidative generation of phosphonyl radicals and silver-assisted fluorine atom transfer is proposed

Silver-Catalyzed Decarboxylative Chlorination of Aliphatic Carboxylic Acids

Decarboxylative halogenation of carboxylic acids, the Hunsdiecker reaction, is one of the fundamental functional group transformations in organic chemistry. As the initial method requires the preparations of strictly anhydrous silver carboxylates, several modifications have been developed to simplify the procedures. However, these methods suffer from the use of highly toxic reagents, harsh reaction conditions, or limited scope of application. In addition, none is catalytic for aliphatic carboxylic acids. In this Article, we report the first catalytic Hunsdiecker reaction of aliphatic carboxylic acids. Thus, with the catalysis of Ag­(Phen)₂OTf, the reactions of carboxylic acids with <i>t</i>-butyl hypochlorite afforded the corresponding chlorodecarboxylation products in high yields under mild conditions. This method is not only efficient and general, but also chemoselective. Moreover, it exhibits remarkable functional group compatibility, making it of more practical value in organic synthesis. The mechanism of single electron transfer followed by chlorine atom transfer is proposed for the catalytic chlorodecarboxylation

Silver-Catalyzed Decarboxylative Bromination of Aliphatic Carboxylic Acids

The silver-catalyzed Hunsdiecker bromination of aliphatic carboxylic acids is described. With Ag­(Phen)₂OTf as the catalyst and dibromoisocyanuric acid as the brominating agent, various aliphatic carboxylic acids underwent decarboxylative bromination to provide the corresponding alkyl bromides under mild conditions. This method not only is efficient and general but also enjoys wide functional group compatibility. An oxidative radical mechanism involving Ag­(II) intermediates is proposed

Targeted Next-Generation Sequencing in Uyghur Families with Non-Syndromic Sensorineural Hearing Loss

<div><p>The mutation spectrum of deafness genes may vary in different ethnical groups. In this study, we investigated the genetic etiology of nonsyndromic deafness in four consanguineous and two multiplex Uyghur families in which mutations in common deafness genes <i>GJB2</i>, <i>SLC26A4</i> and <i>MT-RNR</i>1 were excluded. Targeted next-generation sequencing of 97 deafness genes was performed in the probands of each family. Novel pathogenic mutations were identified in four probands including the p.L416R/p.A438T compound heterozygous mutations in <i>TMC1</i>, the homozygous p.V1880E mutation in <i>MYO7A</i>, c.1238delT frameshifting deletion in <i>PCDH15</i> and c.9690+1G>A splice site mutation in <i>MYO15A</i>. Co-segregation of the mutations and the deafness were confirmed within each family by Sanger sequencing. No pathogenic mutations were identified in one multiplex family and one consanguineous family. Our study provided a useful piece of information for the genetic etiology of deafness in Uyghurs.</p></div

Multi-species sequence alignment showing the evolutionarily conserved residues of p.L416 and p.A438 in <i>TMC1</i> and p.V1880 in <i>MYO7A</i>.

<p>Multi-species sequence alignment showing the evolutionarily conserved residues of p.L416 and p.A438 in <i>TMC1</i> and p.V1880 in <i>MYO7A</i>.</p

Pedigrees and audiograms of Family KLX214 (A) and KLX11 (B).

<p>Temporal bone CT scan of KLX11-1 showed dysplasia of the cochlea (downward arrow in R1) and the vestibule (upward arrow in R2) on the right side (R1, R2) in comparison with the normal inner ear structure on the left side (L1, L2).</p

Pedigrees, genotypes and audiograms of Family KLX10 (A), KLX13 (B), KLX213 (C) and KS1 (D).

<p>Probands were pointed by an arrow.</p