A Recyclable Electrochemical Reduction of Aldehydes and Ketones to Alcohols Using Water as the Hydrogen Source and Solvent.

There are several challenging problems such as the usage of combustible and hazardous hydrogen sources and severe environmental pollution in the conventional reduction of aldehydes/ketones to alcohols. We report here a practical, safe, and green electrochemical reduction, which solves these problems to a large extent. Through an undivided cell, Zn(+) and Sn(-) as the electrode, tetrabutylammonium chloride (TBAC) as the electrolyte, water as the solvent and hydrogen source, a wide range of aldehydes and ketones are converted into the corresponding alcohols in mild conditions. Furthermore, the electrolytes and water can be recycled, and reductive deuteration can be achieved by simply using D2O as the solvent. Finally, the reduction can be smoothly scaled up to a kilogram level.

Photoinduced Tandem Cyanomethylation/Cyclization of Unsaturated Compounds: Access to Cyanomethylated 7- or 5-Membered N-Heterocycles.

A cyanomethylation/cyclization of aryl acetylenes/ethylenes with bromoacetonitrile was finished in a photopromoted condition, which offers an efficient and mild protocol for the preparation of cyanomethylated 7- or 5-membered N-heterocycles with good yields. Meanwhile, trichloroacetonitrile was also compatible with this radical pathway. In addition, a variety of single-crystal X-ray diffraction measurements, scaled-up operations to 1 mmol, functional group transformations of final products, light on/off experiments, and even radial inhibition studies were smoothly performed in this tandem system.

Nitro-Spirocyclization of Biaryl Ynones with tert-Butyl Nitrite: Access to NO2-Substituted Spiro[5,5]trienones.

A metal/peroxide-free involved simple cascade 6-exo-trig spirocyclization of tert-butyl nitrite with biaryl ynones has been finished, which resulted in various NO2-modified spiro[5,5]trienones with good regioselectivity/yields. A variety of scaled-up experiments, reduction/epoxidation operations, and mechanistic studies were performed to verify the merits and spirocyclization process of this radical system. Finally, the structure of the spirocycles was confirmed by single-crystal X-ray diffraction.

Free Radical Promoted Trifluoromethylthiolation of Alkynes to Access SCF3-Containing Dibenzazepines or Dioxodibenzothiazepines.

Persulfate-promoted radical cascade trifluoromethylthiolation of aryl acetylenes with AgSCF3 provides a simple reaction system for the synthesis of SCF3-substituted dibenzazepines or dioxodibenzothiazepines with good Z/E selectivity. The single-crystal X-ray diffraction data confirms the structures of the final products. A series of scaled-up experiments, further transformations, and radical inhibition experiments were operated in the reaction system.

Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes.

An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.

Advances in free-radical alkylation and arylation with organoboronic acids.

Organoboronic acids act as carbon-centered radical precursors that are widely utilized to construct diverse C-C bonds. This review summarizes the advances in this field. The content is divided into four parts according to the different categories of coupling partners with organoboronic acids. The reaction conditions as well as the mechanisms are demonstrated in each part.

Palladium-catalyzed C(sp3)-H nitrooxylation of masked alcohols.

A palladium-catalyzed ß-C(sp3)-H nitrooxylation of aliphatic alcohols with AgNO2 is reported. An 8-formylquinoline-derived oxime is installed as an exo-type directing group for sp3 C-H activation and selectfluor acts as the oxidant. The reaction tolerates a variety of functional groups and shows good selectivity for ß-C-H nitrooxylation of alcohols.

Free Radical-Promoted Monochloroalkylarylation of Alkenes with Chloralkanes.

Free radical-initiated cascade cyclization of unactivated alkenes with chloralkanes, which undergoes selective activation of the α-C(sp3)-H bond of chloralkanes, provides a protocol for the synthesis of chlorinated heterocycles or polycyclic compounds. A series of radical inhibition experiments, radical capture operations, and radical clock tests were studied in this system.

Atom-Transfer Radical Addition of Alcohols to Aliphatic Alkynes.

An intermolecular hydrogen bond-promoted atom-transfer radical addition of simple alcohols to aliphatic alkynes is demonstrated here. Through this strategy, a variety of allyl alcohols can be synthesized in high selectivity and yields. Furthermore, this work reveals the relationship between selectivity and the substrate.

Molecular Oxygen-Promoted General and Site-Specific Alkylation with Organoboronic Acid.

A general alkylating method using organoboronic acid under 1 atm of oxygen is developed. It allows a facile access to a wide range of functionalized molecules with privileged scaffolds in drugs and natural products such as oxindoles, quinolinones, chromones, naphthoquinones, coumarins, and quinolones. In contrast to previous alkylation approaches that generally requiring transition-metal catalysis and a stoichiometric chemical oxidant, the present strategy features metal-free, molecular oxygen as the terminal oxidant and site specificity.

Free-Radical Bromotrifluoromethylation of Olefin via Single-Electron Oxidation of NaSO2CF3 by NaBrO3.

A free-radical bromotrifluoromethylation of olefin by using NaSO2CF3 and NaBrO3 has been achieved. Sodium bromate acts not only as a single-electron oxidant but also as a bromine source. A radical-clock experiment and electron-spin-resonance detection support a radical process.

Recent developments in free-radical-promoted C-Si formation via selective C-H/Si-H functionalization.

As important and valuable alternatives to transition-metal-catalysis, free-radical strategies for C-Si bond construction via selective C-H/Si-H functionalization have been developed recently. These new reactions along with their suggested mechanisms are summarized and discussed here.

A Free-Radical-Promoted Stereospecific Decarboxylative Silylation of α,ß-Unsaturated Acids with Silanes.

A stereospecific decarboxylative silylation of acrylic and propiolic acids with silanes was developed. This reaction represents the first example of decarboxylative C-Si bond formation and provides an efficient and convenient approach to various synthetically useful alkenyl and alkynyl organosilicon compounds through the reaction of α,ß-unsaturated acids with silanes. Spin-trapping and EPR experiments support a radical addition/elimination process.

Transition metal-catalyzed C(vinyl)-C(vinyl) bond formation via double C(vinyl)-H bond activation.

Transition metal-catalyzed oxidative dehydrogenative coupling reactions of Caryl-H bonds with Cvinyl-H bonds to generate a Caryl-Cvinyl bonds have been well developed in recent decades. However, only a few studies have focused on the direct Cvinyl-Cvinyl bond formation via double Cvinyl-H bond activation. Recent developments in this active area have been highlighted in this tutorial review.

Metal-free radical bicyclization/chloroalkylarylation of 1,6-enynes with chloroalkanes.

Free radical initiated bicyclization of 1,6-enynes with chloralkanes, is achieved via selective activation of the C(sp3)-H bond of the chloralkane, resulting in diverse polychlorinated/chlorinated polyheterocycles. Two kinds of transformations and a scaled-up experiment were performed to test the synthetic importance of the organic chlorides. Finally, a range of radical inhibition operations and radical clock tests were explored to support the reaction process.

Radical Three-Component Nitro Spiro-Cyclization of Unsaturated Sulfonamides/Amides to Access NO2-Featured 4-Azaspiro[4.5]decanes.

Free radical three-component nitration/spirocyclization of unsaturated sulfonamides/amides with tert-butyl nitrite was developed for the construction of diverse NO2-revised 4-azaspiro[4.5]decanes. This tandem system featured metal-free participation, simple operation, good selectivity/yields, and a green/low-cost O source. Meanwhile, one nitro-containing complex molecule and a scaled-up operation were performed well to test the synthetic potential of the cascade reaction. Isotopic labeling, radical inhibition experiments, and DFT analysis were carried out to gain insight into the reaction process.

[Epidemic analysis of HIV-1 incidence using BED-CEIA assay in Tianjin, China, 2010].

OBJECTIVE: To explore the epidemic characteristics of HIV-1 recent infection among high-risk populations in Tianjin and to provide reasonable evidence for intervention strategy. METHOD: Blood samples were detected using BED-CEIA to identify recent HIV-1 infection, and HIV/AIDS cases in Tianjin 2010 were collected to analyze epidemic data. RESULTS: 349 of reported HIV/AIDS cases were confirmed from total 777 207 people. ALL of 87 HIV-1 recent infections were males and mainly detected from men who have sex with men (MSM), voluntary counseling and testing (VCT) and STD outpatients, the HIV-1 incidence of each group was 1.48%, 0.38%, 0.17% respectively. There were not significant difference in recent HIV-1 infection rate between other areas and locals. The homosexual transmission was 80.46% among recent HIV-1 infections. CONCLUSION: The results of this study showed that the homosexual contact was primary route of HIV transmission in Tianjin. The infection of HIV was serious among MSM, effective interventions should be taken for HIV/AIDS control and prevention urgently.

A free radical nitration of olefins with NaNO2/I2O5.

We demonstrated herein an I2O5-mediated radical nitration of olefins with NaNO2. A variety of (E)-nitroolefins can be synthesized in high yields and chemoselectivity.

Molecular Oxygen-Mediated Radical Alkylation of C(sp3)-H Bonds with Boronic Acids.

A direct and site-specific alkylation of (sp3)C-H bond with aliphatic boronic acid was achieved. By simply heating glycinates and amines together with alkylboronic acids under an oxygen atmosphere, a variety of unnatural α-amino acids and peptides could be obtained in good yields.

Site-Specific Oxidation of (sp3)C-C(sp3)/H Bonds by NaNO2/HCl.

A site-specific oxidation of (sp3)C-C(sp3) and (sp3)C-H bonds in aryl alkanes by the use of NaNO2/HCl was explored. The method is chemical-oxidant-free, transition-metal-free, uses water as the solvent, and proceeds under mild conditions, making it valuable and attractive to synthetic organic chemistry.