The (o-p-o)-Terphenyl Embedded Calix[2]phyrin(2.2.1.1.1) and Its Cu(II) Complex.

The introduction of a higher arene unit as a structural motif is unprecedented in calixphyrin chemistry. Herein, the syntheses, spectral and structural characterization of heretofore anonymous terphenylene unit (o-p-o) incorporated calixphyrin with fused sp2 meso carbons is reported. The explicitly tailored macrocyclic core is utilized to stabilize the Cu(II) metal ion. The molecular structures of the calixbenziphyrin and Cu(II) complex are unambiguously confirmed by single-crystal X-ray analysis. Moreover, theoretical supports uphold experimental conclusions.

A Formal γ-C-H Functionalization of Carboxylic Acids Guided by Metal-Nitrenoids as an Unprecedented Mechanistic Motif.

Harnessing the key intermediates in metal-catalyzed reactions is one of the most essential strategies in the development of selective organic transformations. The nitrogen group transfer reactivity of metal-nitrenoids to ubiquitous C-H bonds allows for diverse C-N bond formation to furnish synthetically valuable aminated products. In this study, we present an unprecedented reactivity of iridium and ruthenium nitrenoids to generate remote carbocation intermediates, which subsequently undergo nucleophile incorporation, thus developing a formal γ-C-H functionalization of carboxylic acids. Mechanistic investigations elucidated a unique singlet metal-nitrenoid reactivity to initiate an abstraction of γ-hydride to form the carbocation intermediate that eventually reacts with a broad range of carbon, nitrogen, and oxygen nucleophiles, as well as biorelevant molecules. Alternatively, the same intermediate can lead to deprotonation to afford ß,γ-unsaturated amides in a less nucleophilic solvent.

Staphylococcus-associated acute glomerulonephritis in a patient with dermatomyositis.

Staphylococcus-associated glomerulonephritis (SAGN) occurs as a complication of staphylococcal infection elsewhere in the body. Dermatomyositis (DM) can be associated with glomerulonephritis due to the disease per se. We report a case of a 40-year-old male patient with DM who presented with acute kidney injury, and was initially pulsed with methylprednisolone for 3 days, followed by dexamethasone equivalent to 1 mg/kg/day prednisolone. He was subsequently found to have SAGN on kidney biopsy along with staphylococcus bacteraemia and left knee septic arthritis. With proof of definitive infection, intravenous immunoglobulin 2 g/kg over 2 days was given and steroids were reduced. He was treated with intravenous vancomycin. With treatment, the general condition of the patient improved. On day 38, he developed infective endocarditis and died of congestive heart failure subsequently. Undiagnosed staphylococcal sepsis complicating a rheumatological disease course can lead to complications like SAGN, infective endocarditis and contribute to increased morbidity and mortality, as is exemplified by our case.

Recent Advances in Metal-catalyzed Alkylation, Alkenylation and Alkynylation of Indole/indoline Benzenoid Nucleus.

Selective editing of the benzenoid C-H bonds (C4-C7) in indoles/indolines has received great interest because functionalized indoles/indolines are featured in many marketed drugs and natural products. Transition-metal-catalyzed directed C-H functionalization has thus been developed to manipulate the benzenoid core through C-C and C-heteroatom bond formation. This review covers the recent advances in selective C-C bond forming reactions, alkylation, alkenylation and alkynylation, over the benzenoid ring (C4-C7) of indoles/indolines using metal catalysis.

Oxidative C-H/N-H Annulation of Aromatic Amides with Dialkyl Malonates: Access to Isoindolinones and Dihydrobenzoindoles.

A copper-mediated oxidative C-H/N-H annulation of aromatic amides with dialkyl malonates has been presented to afford synthetically valuable dihydrobenzoindoles and isoindolinones. The reaction proceeds through direct oxidative C(sp2)-H/C(sp3)-H coupling followed by an intramolecular N-H/C(sp3)-H dehydrogenative coupling to deliver the target motifs with broad scope and functional group tolerance.

Cp*Co(III)-Catalyzed C-7 C-C Coupling of Indolines with Aziridines: Merging C-H Activation and Ring Opening.

A Cp*Co(III)-catalyzed directing group-assisted C7 C-C coupling of indolines with aziridines has been developed by merging C-H activation and ring opening. The use of cobalt catalyst, detection of a Co(III) intermediate, and late-stage removal of the directing group are important practical features.

Weak Coordination Enabled Switchable C4-Alkenylation and Alkylation of Indoles with Allyl Alcohols.

A weak carbonyl coordination facilitated tunable reactivity between alkenylation and alkylation of indoles at the C4 C-H site is presented using readily accessible allylic alcohols in the presence of Rh catalysis by switching the additives or directing group. Exclusive site selectivity, functional group tolerance, and late-stage modifications are the important practical features.

Weak Coordination-Guided Regioselective Direct Redox-Neutral C4 Allylation of Indoles with Morita-Baylis-Hillman Adducts.

A weak carbonyl coordination-guided regioselective C4 allylation of indoles is demonstrated using the versatile Morita-Baylis-Hillman adduct in the presence of Rh catalysts in a redox-neutral fashion. The substrate scope, functional group diversity, oxidant free character, mechanistic aspects, and synthetic utilities are important practical features.

Cp*Co(III)-Catalyzed Regioselective C2 Amidation of Indoles Using Acyl Azides.

A cobalt-catalyzed C2-selective amidation of indoles using acyl azides has been accomplished. Isotope experiments suggest that C-H activation is reversible. The use of sustainable Co catalysis, functional group diversity, substrate scope, and regioselectivity are the important practical features.

Exploiting Strained Rings in Chelation Guided C-H Functionalization: Integration of C-H Activation with Ring Cleavage.

Strained ring systems are regarded as privileged coupling partners in directed C-H bond functionalization and have emerged as a potential research area in organic synthesis. The inherent ring strain in these systems acts as a driving force, allowing the facile construction of diversified structural scaffolds via integrating C-H activation and ring-scission. The mechanistic underpinnings allows the implementation of a plethora of C-H bonds across plentiful organic substrates, including the less reactive alkyl ones. Considering the synthetic space, this area will foster developments of novel synthetic methods in chelation guided C-H functionalization. This review will focus on recent developments in transition-metal catalyzed chelation assisted concomitant C-H activation and ring scission of strained rings to attain molecular complexity.

Stereospecific Copper(II)-Catalyzed Tandem Ring Opening/Oxidative Alkylation of Donor-Acceptor Cyclopropanes with Hydrazones: Synthesis of Tetrahydropyridazines.

Aerobic copper(II)-catalyzed tandem ring opening and oxidative C-H alkylation of donor-acceptor cyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89-98% enantiomeric excess). The substrate scope, functional group tolerance, dual role of the copper(II) catalyst, and the use of air as an oxidant are the important practical features. A product bearing a 3-bromoaryl group can be subjected to Pd-catalyzed Suzuki coupling with boronic acid in high yield.

Iron-Catalyzed Regioselective Remote C(sp2)-H Carboxylation of Naphthyl and Quinoline Amides.

Iron(III)-catalyzed regioselective direct remote C-H carboxylation of naphthyl and quinoline amides was developed using CBr4 and alcohol. The reaction involves a radical pathway using a coordination activation strategy and single electron transfer process. The use of sustainable iron catalysis, selectivity, and the substrate scope are the important practical features.

Stereospecific assembly of tetrahydroquinolines via tandem ring-opening/oxidative cyclization of donor-acceptor cyclopropanes with N-alkyl anilines.

An aerobic copper-catalyzed tandem reaction of N-alkyl anilines with donor-acceptor cyclopropanes is presented for the construction of tetrahydroquinolines via a sequential stereospecific ring opening and oxidative cyclization. The catalyst plays a dual role as a Lewis acid as well as being a redox catalyst. The use of air as an oxidant and the broad substrate scope are the important practical features.

Transition-metal-catalyzed site-selective C7-functionalization of indoles: advancement and future prospects.

C7-Decorated indoles are important structural motifs present in a plethora of bioactive and pharmaceutical compounds. Early stage developments for C7 modifications were realized through directed metallation (DOM) and subsequent quenching with suitable electrophiles or by halogenation with Cu(ii) halides. Direct C-7 functionalization of indoles is comparatively difficult compared to functionalization at C-2 and C-3 positions owing to the inherent reactivity of the pyrrole-type ring. However, recently transition-metal-catalyzed auxiliary assisted site-selective C-7 functionalization of indoles has emerged as an elegant synthetic tool for carbon-carbon and carbon-heteroatom bond formation to diversify the indoles. This article covers the advancement, application and mechanistic underpinnings of the evolved transformations of the otherwise inert C7-H bond up to October 2018.

Ru(ii)-Catalyzed C7-acyloxylation of indolines with carboxylic acids.

Ruthenium(ii)-catalyzed site-selective C7-acyloxylation of indolines with carboxylic acids is presented. The substrate scope and functional group tolerance are important practical features. The kinetic isotope studies suggest that C-H bond activation may be the rate-determining step.

Stereospecific Ring Opening and Cycloisomerization of Aziridines with Propargylamines: Synthesis of Functionalized Piperazines and Tetrahydropyrazines.

Stereospecific Cu-catalyzed nucleophilic ring opening of N-sulfonylaziridines with propargylamines and subsequent hydroamination afford piperazines, which leads to double-bond isomerization to furnish tetrahydropyrazines. Optically active aziridines can be cross-coupled with high enantiomeric purities (>98% ee).

Note: Design of FPGA based system identification module with application to atomic force microscopy.

The science of system identification is widely utilized in modeling input-output relationships of diverse systems. In this article, we report field programmable gate array (FPGA) based implementation of a real-time system identification algorithm which employs forgetting factors and bias compensation techniques. The FPGA module is employed to estimate the mechanical properties of surfaces of materials at the nano-scale with an atomic force microscope (AFM). The FPGA module is user friendly which can be interfaced with commercially available AFMs. Extensive simulation and experimental results validate the design.

Ruthenium(II)-Catalyzed Positional Selective C-H Oxygenation of N-Aryl-2-pyrimidines.

Efficient Ru-catalyzed regioselective C-H oxygenation of N-aryl-2-pyrimidines is described with aryl carboxylic acids in the presence of AgSbF6 as an additive and Ag2CO3 as an oxidant. The reaction can be extended to alkyl, heteroaryl, and α,ß-unsaturated carboxylic acids. The regioselectivity, broad substrate scope, and functional group tolerance are the significant practical advantages.

Copper-mediated regioselective C-H etherification of naphthylamides with arylboronic acids using water as an oxygen source.

The copper-mediated regioselective C-H activation and C-O bond formation of naphthylamides with arylboronic acids has been developed using water as an oxygen source. The kinetic isotope study suggests that C-H bond activation is the rate-determining step. The H2O18 labelling experiment reveals the incorporation of oxygen from water. The substrate scope, functional group diversity and post synthetic utilities are the important practical features.

Correction: Copper-mediated regioselective C-H etherification of naphthylamides with arylboronic acids using water as an oxygen source.

Correction for 'Copper-mediated regioselective C-H etherification of naphthylamides with arylboronic acids using water as an oxygen source' by Subhasish Roy et al., Chem. Commun., 2018, DOI: 10.1039/c8cc02158a.