Tetraaryldisilanes as a novel strategic radical reagent

Visible-light-mediated Minisci C-H alkylation of heteroarenes with unactivated alkyl halides using O2 as an oxidant

Herein, we report a protocol for direct visible-light-mediated Minisci C-H alkylation of heteroarenes with unactivated alkyl halides using molecular oxygen as an oxidant at room temperature. This mild protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope. Notably, functionalization of (iso)quinolines, pyridines, phenanthrolines, quinazoline, and other heterocyclic compounds with unactivated primary, secondary, and tertiary alkyl halides proceeds smoothly under the standard conditions. The robustness of this protocol is further demonstrated by the late-stage functionalization of complex nitrogen-containing natural products and drugs.

Hydrodebromination of allylic and benzylic bromides with water catalyzed by a rhodium porphyrin complex

Hydrodebromination of allylic and benzylic bromides was successfully achieved by a rhodium porphyrin complex catalyst using water as the hydrogen source without a sacrificial reductant. Mechanistic investigations suggest that bromine atom abstraction via a rhodium porphyrin metalloradical operates to give the rhodium porphyrin alkyl species and the subsequent hydrolysis of the rhodium porphyrin alkyl species to a hydrocarbon product is a key step to harness the hydrogen from water.

Versatile cross-dehydrogenative coupling of heteroaromatics and hydrogen donors via decatungstate photocatalysis

A facile sunlight-induced derivatization of heteroaromatics via photocatalyzed C-H functionalization in amides, ethers, alkanes and aldehydes is described. Tetrabutylammonium decatungstate (TBADT) was used as the photocatalyst and allowed to carry out the process under mild conditions.

Introduction of Quinolines and Isoquinolines onto Nonactivated α-C-H Bond of Tertiary Amides through a Radical Pathway

Treatment of quinolines and isoquinolines with benzoyl peroxide in tertiary amides, such as N,N-dimethylacetamide, N,N-dimethylpropionamide, and N-acetylpyrrolidine, etc., under irradiation with a Hg lamp in the temperature range of 35 °C to 40 °C gave C-C-bonded quinolines and isoquinolines bearing amide groups with high regioselectivity in good to moderate yields, respectively, under transition-metal-free conditions.

Aqueous Reduction of Iodosteroids to Deoxysteroids

A new method for the reduction of iodosteroids to deoxysteroids has been developed using Zn, HCOOH and a catalytic amount of Aliquat 336 in water. In total, 13 iodosteroids were reduced in good to excellent yields. The higher solubilities of the substrates lead to the faster reactions, and the aqueous reaction was efficiently accelerated by granular polytetrafluoroethylene. The advantage of the aqueous system over eight organic solvents has also been demonstrated.

Radical reactions in aqueous medium using (Me3Si)3SiH

(Me3Si)3SiH was used as a successful reagent in a variety of radical-based transformations in water. The system comprising substrate, silane, and initiator (ACCN) mixed in aqueous medium at 100 degrees C worked well for both hydrophilic and hydrophobic substrates, with the only variation that an amphiphilic thiol was also needed in case of the water-soluble compounds.

Zinc- and Indium-Mediated Ring-Expansion Reaction of α-Halomethyl Cyclic β-Keto Esters in Aqueous Alcohol

Radical ring-expansion reaction of various alpha-halomethyl cyclic beta-keto esters and alpha-halomethyl benzocyclic beta-keto esters and chain-extension reaction of alpha-halomethyl beta-keto esters with zinc powder and indium powder in refluxing aqueous alcohol were carried out to generate the corresponding ring-expansion and chain-extension products. As the results indicate, it was found zinc powder was more effective than indium powder to give the corresponding ring-expanded products in quite good yields. Moreover, the addition of zinc bromide as Lewis acid showed an increase of the yields, depending on the substrates. The present reaction conditions are highly effective, simple, and environmentally friendly.

Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2

[see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.