Influence of Polarity and Activation Energy in Microwave-Assisted Organic Synthesis (MAOS).

The aim of this work was to determine the parameters that have a decisive role in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions can be improved under microwaves. For this purpose, a computational study has been carried out on a variety of reactions that … Continue reading

The Issue of ‘Molecular Radiators’ in Microwave-Assisted Reactions. Computational Calculations in Ring Closing Metathesis (RCM).

A DFT computational mechanistic study of the ring closing metathesis (RCM) reaction of diallyl ether or N,N-diallyl-p-toluenesulfonamide catalyzed by a second generation Grubbs-type ruthenium carbene complex has been carried out. This study was performed at PCM(CH2Cl2)-B3LYP/6-311+G(2d,p)//B3LYP/SDD theory level. The aim of this work was to shed light on the influence that microwave irradiation has in … Continue reading

Exfoliation of Graphite with Triazine Derivatives under Ball-Milling Conditions: Preparation of Few-Layer Graphene via Selective Noncovalent Interactions

A ball-milling treatment can be employed to exfoliate graphite through interactions with commercially available melamine under solid conditions. This procedure allows the fast production of relatively large quantities of material with a low presence of defects. The milling treatment can be modulated in order to achieve graphene flakes with different sizes. Once prepared, the graphene … Continue reading

DFT-Studies on Cobalt-Catalyzed Cyclotrimerization Reactions. Mechanism and Origin of Reaction Improvement under Microwave Irradiation.

A DFT computational mechanistic study of the [2+2+2] cyclotrimerization of a diyne with benzonitrile, catalyzed by a cobalt complex, has been carried out. Three alternative catalytic cycles have been examined together with the precatalytic step (responsible for the induction period). The favored mechanism takes place via an intramolecular metal-assisted [4+2] cycloaddition. The beneficial role of … Continue reading

HOT OBC Article: DFT to predict outcome of microwave-assisted organic reactions

Congratulations to the authors! Some researchers of our group had their manuscript, ‘“In silico” mechanistic studies as predictive tools in microwave-assisted organic synthesis’, highligthed as an Organic & Biomolecular Chemistry Hot Article and has been made free to access for four weeks. It has also been highlighted on the OBC blog. We would be delighted … Continue reading

Microwave-assisted reactions of nitroheterocycles with dienes. Diels–Alder and tandem hetero Diels–Alder/[3,3] sigmatropic shift

Diels–Alder cycloaddition of 3-nitro-1-(p-toluenesulfonyl)indole 1 with dienes 2–6 under microwave irradiation in solvent-free conditions gave carbazole derivatives after elimination of the nitro group and in situ aromatization. While 3-nitro-1-(p-toluenesulfonyl)pyrrole 11 afforded indole derivatives, 4-nitro- 1-(p-toluenesulfonyl)pyrazole 13 with cyclohexadiene 2 did not afford the expected cycloadduct but instead gave 1-cyclohexen-2-ylpyrazole 16. This process occurred by hydrolysis … Continue reading

“In silico” Mechanistic studies as predictive tools in Microwave-Assisted Organic Synthesis

Computational calculations can be used as a predictive tool in Microwave-Assisted Organic Synthesis (MAOS). A DFT study on Intramolecular Diels–Alder reactions (IMDA) indicated that the activation energy of the reaction and the polarity of the stationary points are two fundamental parameters to determine “a priori” if a reaction can be improved by using microwave irradiation.

Selectivity under microwave irradiation. Benzylation of 2-pyridone: an experimental and theoretical study

The reaction of 2-pyridone with benzyl bromide in the absence of base and under solvent-free conditions has been studied experimentally and by computational methods. This reaction was one of the first reported examples in which modification of selectivity under microwave irradiation was observed. C- and/ or N-alkylations were obtained depending on the benzyl halide and … Continue reading