Silver oxide(I) promoted Conia-ene/radical cyclization for a straightforward access to furan derivatives

A novel access to fused furan cores using silver oxide(I) has been developed. Mechanistic investigations would indicate the involvement of a Conia-ene reaction/radical cyclization for an expedient path to complex...

Mechanistic investigations on a homogeneous ruthenium Guerbet catalyst in a flow reactor

A mechanistic investigation on the ethanol self-condensation reaction (Guerbet reaction) catalyzed by a bis(pyridylimino)isoindolate Ru(ii) catalyst was performed using a specifically designed continuously-stirred tank reactor (CSTR).

Photo-induced catalytic halopyridylation of alkenes

The Mizoroki-Heck reaction and its reductive analogue are staples of organic synthesis, but the ensuing products often lack a chemical handle for further transformation. Here we report an atom-economical cross-coupling of halopyridines and unactivated alkenes under photoredox catalysis to afford a series of alkene halopyridylation products. This protocol with mild and redox neutral conditions contributes broad substrate scope. As a complement to conventional Heck-type reaction, this radical process avoids the involvement of β-H elimination and thus useful pyridyl and halide groups could be simultaneously and regioselectively incorporated onto alkenes. The success depends on TFA-promoted domino photocatalytic oxidative quenching activation and radical-polar crossover pathway. Plausible mechanism is proposed based on mechanistic investigations. Moreover, the reserved C − X bonds of these products are beneficial for performing further synthetic elaborations.

Indium(III)-Catalyzed Synthesis of Primary Carbamates and N-Substituted Ureas

An indium triflate-catalyzed synthesis of primary carbamates from alcohols and urea as an ecofriendly carbonyl source has been developed. Various linear, branched, and cyclic alcohols were converted into the corresponding carbamates in good to excellent yields. This method also provided access to N-substituted ureas by carbamoylation of amines. All the products were obtained by simple filtration or crystallization, without the need for chromatographic purification. Mechanistic investigations suggest that the carbamoylation reaction proceeds through activation of urea by O-coordination with indium, followed by nucleophilic attack by the alcohol or amine on the carbonyl center of urea. The inexpensive and easily available starting materials and catalyst, the short reaction times, and the ease of product isolation highlight the inherent practicality of the developed method.

Base-Mediated Site-Selective Hydroamination of Alkenes

We present a base-mediated hydroamination protocol, using substoichiometric amounts of a hydrosilane and potassium tert-butoxide, that operates under mild conditions at 30 oC. Many aryl- and heteroatom-substituted olefins as well as aryl amines are tolerated, affording the desired products with complete regioselectivity. Preliminary mechanistic investigations reveal a non-radical pathway for hydroamination. A sequential remote hydroamination strategy involving an initial Fe-catalysed olefin isomerisation followed by our base-mediated hydroamination was also developed to directly access β-arylamines from terminal aliphatic alkenes.