Recent Advances in Electrochemical Carboxylation with CO.

ConspectusCarbon dioxide (CO) is recognized as a greenhouse gas and a common waste product. Simultaneously, it serves as an advantageous and commercially available C1 building block to generate valuable chemicals. Particularly, carboxylation with CO is considered a significant method for the direct and sustainable production of important carboxylic acids.

A Bimolecular Homolytic Substitution-Enabled Platform for Multicomponent Cross-Coupling of Unactivated Alkenes.

The construction of C()-C() bonds remains one of the most difficult challenges in cross-coupling chemistry. Here, we report a photoredox/nickel dual catalytic approach that enables the simultaneous formation of two C()-C() linkages via trimolecular cross-coupling of alkenes with alkyl halides and hypervalent iodine-based reagents. The reaction harnesses a bimolecular homolytic substitution (S2) mechanism and chemoselective halogen-atom transfer (XAT) to orchestrate the regioselective addition of electrophilic and nucleophilic alkyl radicals across unactivated alkenes without the need for a directing auxiliary.

Electroreductive Dicarboxylation of Unactivated Skipped Dienes with CO.

Carboxylation of easily available alkenes with CO is highly important to afford value-added carboxylic acids. Although dicarboxylation of activated alkenes, especially 1,3-dienes, has been widely investigated, the challenging dicarboxylation of unactivated 1,n-dienes (n>3) with CO remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO via electrochemistry, affording valuable dicarboxylic acids.

Electrochemical reactor dictates site selectivity in N-heteroarene carboxylations.

Pyridines and related N-heteroarenes are commonly found in pharmaceuticals, agrochemicals and other biologically active compounds. Site-selective C-H functionalization would provide a direct way of making these medicinally active products. For example, nicotinic acid derivatives could be made by C-H carboxylation, but this remains an elusive transformation.

Electrochemical Ring-Opening Dicarboxylation of Strained Carbon-Carbon Single Bonds with CO: Facile Synthesis of Diacids and Derivatization into Polyesters.

Diacids are important monomers in the polymer industry to construct valuable materials. Dicarboxylation of unsaturated bonds, such as alkenes and alkynes, with CO has been demonstrated as a promising synthetic method. However, dicarboxylation of C─C single bonds with CO has rarely been investigated.

Nickel-catalyzed electrochemical carboxylation of unactivated aryl and alkyl halides with CO.

Electrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C-C bonds by using electron as the clean reductant. However, activated substrates are used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO.

α-Amino Acids and Peptides as Bifunctional Reagents: Carbocarboxylation of Activated Alkenes via Recycling CO.

Carboxylic acids, including amino acids (AAs), have been widely used as reagents for decarboxylative couplings. In contrast to previous decarboxylative couplings that release CO as a waste byproduct, herein we report a novel strategy with simultaneous utilization of both the alkyl and carboxyl components from carboxylic acids. Under this unique strategy, carboxylic acids act as bifunctional reagents in the redox-neutral carbocarboxylation of alkenes.

Visible-Light-Driven External-Reductant-Free Cross-Electrophile Couplings of Tetraalkyl Ammonium Salts.

Cross-electrophile couplings between two electrophiles are powerful and economic methods to generate C-C bonds in the presence of stoichiometric external reductants. Herein, we report a novel strategy to realize the first external-reductant-free cross-electrophile coupling via visible-light photoredox catalysis. A variety of tetraalkyl ammonium salts, bearing primary, secondary, and tertiary C-N bonds, undergo selective couplings with aldehydes/ketone and CO.

Angelicin regulates LPS-induced inflammation via inhibiting MAPK/NF-κB pathways.

Background: Angelicin is a furocoumarin found in Psoralea corylifolia L. fruit. The purpose of this study was to investigate the protective ability of angelicin against inflammation in lipopolysaccharide (LPS)-stimulated RAW 264.

[Myocardial protective effect of acetylcholine against ischemia/reperfusion injury and its underlying mechanism].

Objective: To determine whether the caidioprotection of acetylcholine (ACh) against ischeniia/reperftision (I/R) injury is re-kited to mitochondrial permeability transition pore (MEW) and mitochondrial AW-sensitive potassium channel (mitoK(ATP)).

Methods: Male Sprague-Dawley rats were used for Langendorif isolated bean perkision. The hearts were subjected to global ischemia for 30 mm followed by 120 rein of reperfusion and the left ventricular hemodynaniic parameters were measured.

Mitochondrial pores modulate the protective effect of acetylcholine on ventricular myocytes during ischemia/reperfusion injury.

In this study, we investigated the cardioprotective effect of acetylcholine (ACh) via modulation of mitochondrial permeability transition pore (MPTP) opening through the mitochondrial ATP-sensitive potassium channel (mitoK(ATP) channel). In isolated ventricular myocytes from male Sprague-Dawley rats, 0.1 micromol/L ACh was administered for 6 min, before 30 min of simulated ischemia and 30 min of reperfusion (I/R).

Antifungal triterpene glycosides from the sea cucumber Holothuria (Microthele) axiloga.

Three new holostan-type triterpene glycosides, arguside F (1), impatienside B (2), and pervicoside D (3), together with a known saponin, holothurin B ( 4) were isolated from the sea cucumber Holothuria (Microthele) axiloga H. L. Clark.

Antifungal triterpene glycosides from the sea cucumber Bohadschia marmorata.

Four new holostan-type triterpene glycosides, marmoratoside A ( 1), 17 alpha-hydroxy impatienside A ( 2), marmoratoside B ( 3), 25-acetoxy bivittoside D ( 4), together with two known triterpene glycosides, impatienside A ( 5) and bivittoside D ( 6), were isolated from the sea cucumber Bohadschia Marmorata Jaeger. On the basis of spectroscopic analyses, including two-dimensional NMR techniques, and chemical reactions, the structures of the new triterpene glycosides were elucidated. Compounds 1, 2, 5, and 6 exhibited significant antifungal activity against six strains (0.

Argusides B and C, two new cytotoxic triterpene glycosides from the sea cucumber Bohadschia argus Jaeger.

Two new triterpene glycosides, argusides B and C (1 and 2, resp.), have been isolated from the sea cucumber Bohadschia argus Jaeger collected in the South China Sea. Their structures have been established by spectral analysis (2D-NMR and ESI-MS) and chemical evidence.

Argusides D and E, two new cytotoxic triterpene glycosides from the sea cucumber Bohadschia argus Jaeger.

Two new triterpene glycosides, argusides D and E (1 and 2, resp.), have been isolated from the sea cucumber Bohadschia argus Jaeger collected in the South China Sea. Their structures have been established by spectral analysis (ESI-MS, and 1D- and 2D-NMR) and chemical evidence.

[Delta-opioid receptor mediates the cardioprotective effect of ischemic postconditioning].

Aim: To investigate the effect of 8-opioid receptors in the cardioprotection elicited by ischemic postconditioning and the underlying mechanism.

Methods: The isolated perfused hearts of male Sprague-Dawley rats were subjected to 30 min of global ischemia followed by 120 min of reperfusion. Formazan content of myocardium was measured spectrophotometrically, and the activity of lactate dehydrogenase (LDH) in the coronary effluent was measured.