Reductive Deamination with Hydrosilanes Catalyzed by B(C6F5)3

The strong boron Lewis acid tris(pentafluorophenyl)borane B(C₆F₅)₃ is known to catalyze the dehydrogenative coupling of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C?N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition‐metal‐free reductive deamination of a broad range of amines as well as heterocumulenes such as an isocyanate and an isothiocyanate.     

Bioinspired Metal-Free Formal Decarbonylation of α-Branched Aliphatic Aldehydes at Ambient Temperature

A sequence of a Baeyer–Villiger oxidation and a Lewis acid-promoted reduction of the resulting formate with Et₃SiH enabled the metal-free formal decarbonylation of tertiary and secondary aliphatic aldehydes. The new methodology mimics the biosynthetic decarbonylation pathway through oxidative C−C bond cleavage rather than the C(O)−H bond activation known from conventional Tsuji–Wilkinson-type reactions. The substrate scope is complementary to existing transition-metal-catalyzed protocols.     

Application of Visible‐to‐UV Photon Upconversion to Photoredox Catalysis: The Activation of Aryl Bromides

The activation of aryl–Br bonds was achieved by sequential combination of a triplet–triplet annihilation process of the organic dyes, butane‐2,3‐dione and 2,5‐diphenyloxazole, with a single‐electron‐transfer activation of aryl bromides. The photophysical and chemical steps were studied by time‐resolved transient fluorescence and absorption spectroscopy with a pulsed laser, quenching experiments, and DFT calculations.     

Visible Light Driven Hydro‐/Deuterodefunctionalization of Anilines

The defunctionalization of anilines is an important strategy in aromatic‐substitution chemistry. Herein, we report on visible light mediated hydro‐ and deuterodediazonations in solutions of DMF. The mild reaction conditions (DMF, RT, no additives) tolerate various functional groups and allow the site‐specific introduction of D atoms to the arene. Mechanistic investigations indicate the participation of photoredox and radical chain pathways and competing abstraction of methyl and formyl hydrogen atoms from DMF.     

A Titanium-Catalyzed Reductive α-Desulfonylation

A titanium(III)-catalyzed desulfonylation gives access to functionalized alkyl nitrile building blocks from α-sulfonyl nitriles, circumventing traditional base-mediated α-alkylation conditions and strong single electron donors. The reaction tolerates numerous functional groups including free alcohols, esters, amides, and it can be applied also to the α-desulfonylation of ketones. In addition, a one-pot desulfonylative alkylation is demonstrated. Preliminary mechanistic studies indicate a catalyst-dependent mechanism involving a homolytic C−S cleavage.     

Injectable Capsaicin for the Management of Pain Due to Osteoarthritis

Capsaicin is a potent agonist of the TRPV1 channel, a transduction channel that is highly expressed in nociceptive fibers (pain fibers) throughout the peripheral nervous system. Given the importance of TRPV1 as one of several transduction channels in nociceptive fibers, much research has been focused on the potential therapeutic benefits of using TRPV1 antagonists for the management of pain. However, an antagonist has two limitations. First, an antagonist in principle generally only affects one receptor. Secondly, most antagonists must have an ongoing presence on the receptor to have an effect. Capsaicin overcomes both liabilities by disrupting peripheral terminals of nociceptive fibers that express TRPV1, and thereby affects all of the potential means of activating that pain fiber (not just TRPV1 function). This disruptive effect is dependent on the dose and can occur within minutes. Thus, unlike a typical receptor antagonist, continued bioavailability at the level of the receptor is not necessary. By disrupting the entire terminal of the TRPV1-expressing nociceptive fiber, capsaicin blocks all the activation mechanisms within that fiber, and not just TRPV1 function. Topical capsaicin, an FDA approved treatment for neuropathic pain, addresses pain from abnormal nociceptor activity in the superficial layers of the skin. Effects after a single administration are evident over a period of weeks to months, but in time are fully reversible. This review focuses on the rationale for using capsaicin by injection for painful conditions such as osteoarthritis (OA) and provides an update on studies completed to date.     

Regeneration of a Conjugated sp2 Graphene System through Selective Defunctionalization of Epoxides by Using a Proven Synthetic Chemistry Mechanism

Graphene is a promising material capable of driving technological advancement. It is, however, a challenge to obtain pristine graphene in large quantities given the limitation of current synthetic methods. Among the numerous methods available, the chemical approach provides an optimistic outlook and has garnered much interest within the graphene community as a potential alternative. One of the most crucial steps of the chemical approach is the chemical reduction of graphene oxide as this dictates the final quality of the graphene sheets. In recent years, much of the focus has shifted to the usage of established reducing agents or oxygen removal reagents, frequently applied in organic chemistry, onto a graphene oxide platform. Herein, the selective removal of epoxide groups and subsequent regeneration of disrupted conjugated sp² system is highlighted, based on the synergistic effect of indium and indium(I) chloride. The morphological, structural, and electrical properties of the resulting graphene were fully characterized with X‐ray photoelectron, Fourier transform IR, solid‐state ¹³C NMR, and Raman spectroscopy; thermogravimetric analysis; scanning electron microscopy; and conductivity measurements. The as‐prepared graphene showed a tenfold increase in conductivity against conventional graphene treated with hydrazine reducing agent and demonstrated a high dispersion stability in ethanol. Moreover, the selective defunctionalization of the epoxide groups provides opportunities for potential tailoring of graphene properties for prospective applications.