Recent Advances in Aerobic Oxidative of C-H Bond by Molecular Oxygen Focus on Heterocycles.

Aerobic oxidative cross-coupling represents one of the most straightforward and atom-economic methods for construction of C-C and C-X (X=N, O, S, or P) bonds using air as a sustainable external oxidant. The oxidative coupling of C-H bonds in heterocyclic compounds can effectively increase their molecular complexity by introducing new functional groups through C-H bond activation, or by formation of new heterocyclic structures through cascade construction of two or more sequential chemical bonds. This is very useful as it can increase the potential applications of these structures in natural products, pharmaceuticals, agricultural chemicals, and functional materials. This is a representative overview of recent progress since 2010 on green oxidative coupling reactions of C-H bond using O2 or air as internal oxidant focus on Heterocycles. It aims to provide a platform for expanding the scope and utility of air as green oxidant, together with a brief discussion on research into the mechanisms behind it.

Efficient Aerobic Oxidative Coupling of Methyl Heteroarenes with Indoles.

Direct oxidative coupling of inert C(sp3 )-H bond has been a great challenge. Herein, an environmentally friendly aerobic oxidative coupling of α-methyl substituted N-heteroarenes with indoles is reported. A variety of diheteroaryl ketones were prepared in good yields (up to 72 %). This protocol features simple operation and broad substrates scope (26 examples). Significantly, a plausible mechanism about catalytic cycle was proposed, and two key intermediates were confirmed by high resolution mass spectrometry.

The C(sp3)-H bond functionalization of thioethers with styrenes with insight into the mechanism.

A metal-free inactive C(sp3)-H bond functionalization of thioethers with styrenes using TBHP as an initiator and DBU as a base has been developed. This transformation has broken through the low activity of thioethers and realized moderate yields. Herein extended experiments were conducted to confirm the radical relay process, reaction energy and intermediate transformations.

Copper-Catalyzed Aldehyde Exchanged Amidation.

The synthesis of bioactive amides has been the pursuit of chemists. Herein secondary amides incorporated with an aldehyde group were first generated using aldehydes and secondary amines. Various (hetero)aryl aldehydes and even aliphatic aldehydes (>40 examples) were converted into the desired products in moderate to excellent yields (up to 89%). A plausible mechanism involving a Cu(I/II/III) catalytic cycle combined with radical rearrangement was proposed and confirmed with four key intermediates detected by high-resolution mass spectrometry.

Rare-Earth Y(OTf)3 Catalyzed Coupling Reaction of Ethers with Azaarenes.

Rare-earth catalysis has become a hot topic in the field of catalytic organic reaction. Chain ethers mostly have lower reactivity and lower boiling points which limited their reaction scope. Herein, we found a rare-earth Y(OTf)3 can catalyze the coupling reaction of ethers especially chain ethers and thioethers with azaarenes. This protocol features simple operations, a broad substrate scope (31 examples), moderate to good yields (up to 85%), and atom economy.

Carotid Endarterectomy and Carotid Artery Stenting Lead to Improved Cognitive Performance in Patients with Severe Carotid Artery Stenosis.

In patients with severe carotid artery stenosis, the effects of carotid artery reopening, achieved either by carotid endarterectomy (CEA) or carotid artery stenting (CAS), on cognitive functions remain elusive. Herein, we conducted a prospective study to determine whether and to what extent CEA and CAS affected cognitive performance. Patients admitted to the Department of Neurology or Vascular Surgery in Nanjing First Hospital from December 2012 to March 2015 with a diagnosis of severe carotid artery stenosis (>70%) were included in the study. Among them, 77 patients underwent CEA, 81 patients underwent CAS, and 77 patients who refused to receive aforementioned interventions were enrolled in control group. Of note, all patients in this study received basic pharmacological treatment according to the American Heart Association/American Stroke Association guidelines. Cognitive functions were evaluated by a broad spectrum of neuropsychological tests including the Mini-mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA) and event related potential P300 on the day prior to and at 3 months after indicated intervention. When compared with basic pharmacological treatment, both CEA and CAS significantly increased the scores of MMSE and MoCA at 3 months following procedures. Meanwhile, a significant reduction of P300 score was also observed in patients underwent CEA or CAS. In addition, the changes in MMSE, MoCA and P300 scores over time between CEA and CAS groups were not statistically significant. Taken together, our findings suggest an improvement of cognitive functions following carotid artery reopening. Meanwhile, the beneficial effects of CEA and CAS on cognitive performance seem to be equivalent.

Chemokine stromal cell-derived factor 1/CXCL12 increases homing of mesenchymal stem cells to injured myocardium and neovascularization following myocardial infarction.

BACKGROUND: Heart failure due to ischemic heart disease is still a major health problem. Myocardium regeneration emerges as a novel therapeutic method for treating myocardial infarction (MI). However, it is affected by many factors. The present study was aimed to investigate the effect of chemokine stromal cell-derived factor 1 (SDF-1)/CXCL12 on mesenchymal stem cells (MSCs) homing to injured myocardium in a rat myocardial infarction model. METHODS: A rat myocardial infarction model was established by permanent left anterior descending branch ligation. Mesenchymal stem cells from donor rats were cultured in IMDM and labeled with bromodeoxyuridine. The rats were divided into two groups. SDF-1 expression was measured by in situ hybridization and immunohistochemistry in the sham operated or infarcted hearts at 1, 2, 4, 7, 14 and 28 days post operation in the SDF-1 detection group. The rats in the intervention groups were injected with SDF-1, anti-SDF-1 antibody or saline 4 days after myocardial infarction. Then, a total of 5 x 10(6) cells in 2.5 ml of phosphate-buffered saline were injected through the tail vein. The number of the labeled MSCs in the infarcted hearts was counted on the 3rd day post injection. Cardiac function and blood vessel density were assessed on the 28th day post injection. RESULTS: Self-generating SDF-1 expression was increased at the first day post MI, peaked at the 7th day and decreased thereafter while it remained unchanged in sham operated hearts. The MSCs enrichment in the host hearts were more abundant in the MI groups than in the non-MI group (P = 0.000); the MSCs enrichment in the host hearts were more abundant in the SDF-1 injected group than in the anti-SDF-1 antibody and saline injected groups (P = 0.000). Cardiac function was improved more in the SDF-1 injected group than in the anti-SDF-1 antibody and saline injected groups (P = 0.000). Neovascularization in the SDF-1 injected group increased significantly compared to the other groups (P = 0.000). CONCLUSION: Myocardial SDF-1 expression was increased only in the early phase post MI. SDF-1 may enhance MSCs homing to the injured heart and improve cardiac function by promoting neovascularization.