An efficient and fast synthesis of 4-aryl-3,4-dihydrocoumarins by (CF3SO3)3Y catalysis under microwave irradiation

A highly enantioselective Friedel–Crafts reaction of 3,5-dimethoxylphenol with nitroolefins mediated by a bifunctional quinine derived thiourea catalyst

A useful and highly enantioselective Friedel–Crafts reaction of 3,5-dimethoxylphenol with nitroolefins catalyzed by a bifunctional quinine derived thiourea catalyst was developed.

One-pot C–C/C–O bond formation: synthesis of spirocyclic lactones

An efficient and practical method for the synthesis of novel spiro(tri or tetra)cyclic lactones via the formation of C–C and C–O bonds in one-pot is presented.

Synthesis and DPPH radical scavenging activity of novel compounds obtained from tyrosol and cinnamic acid derivatives

Novel compounds exhibiting DPPH radical scavenging activity were synthesised. The key step was the trifluoroacetic acid-mediated hydroarylation of cinnamic ester with tyrosol.

Solvent-free synthesis, DNA-topoisomerase II activity and molecular docking study of new asymmetrically N,N'-substituted ureas

A new series of asymmetrically N,N'-substituted ureas 20–25 was prepared using solvent free conditions, which is an eco-friendly methodology, starting with Schiff bases derived from cinnamaldehyde and p-substituted anilines, which are subsequently submitted to reduction reactions that afford the corresponding asymmetric secondary amines. All of the intermediates were prepared using solvent free reactions, which were compared to traditional methodologies. All of the reactions required a remarkably short amount of time and provided good yields when solvent free conditions were employed compared to other methodologies. The DNA-topoisomerase II-α (topo II-α) activity was evaluated in relaxation assays, which showed that all of the compounds inhibited the enzyme activity at 10 μM, except for urea 24. Furthermore, a molecular docking study indicated that the compounds 20–25 binding to the topo II-α are able to interact with the same binding site as the anticancer drug etoposide, suggesting that the ureas could inhibit the enzyme by the same mechanism of action observed for etoposide, which prevents re-ligation of the DNA strands.

Facile synthesis of 4-substituted 3,4-dihydrocoumarins via an organocatalytic double decarboxylation process

3,4-Dihydrocoumarins, considered to be valuable building blocks, have attracted considerable attention due to their various biological activities. Herein, we have documented an efficient and convenient double decarboxylation process for the synthesis of 4-substituted 3,4-dihydrocoumarin in moderate to excellent yields under mild reaction conditions (up to 98%).

Microwave-assisted synthesis of new N₁,N₄-substituted thiosemicarbazones

We present an efficient procedure for the synthesis of thirty-six N₁,N₄-substituted thiosemicarbazones, including twenty-five ones that are reported for the first time, using a microwave-assisted methodology for the reaction of thiosemicarbazide intermediates with aldehydes in the presence of glacial acetic acid in ethanol and under solvent free conditions. Overall reaction times (20-40 min when ethanol as solvent, and 3 min under solvent free conditions) were much shorter than with the traditional procedure (480 min); satisfactory yields and high-purity compounds were obtained. The thiosemicarbazide intermediates were obtained from alkyl or aryl isothiocyanates and hydrazine hydrate or phenyl hydrazine by stirring at room temperature for 60 min or by microwave irradiation for 30 min, with lower yields for the latter. The preliminary in vitro antifungal activity of thiosemicarbazones was evaluated against Aspergillus parasiticus and Candida albicans.

Lewis acid-catalyzed diastereoselective hydroarylation of benzylidene malonic esters

Herein we report that simple Lewis acids catalyze the hydroarylation of benzylidene malonates with phenols. Ultimately, 3,4-disubstituted dihydrocoumarins are obtained via a hydroarylation-lactonization sequence. Moreover, the dihydrocoumarins are formed with a high degree of diastereoselectivity favoring the trans stereoisomer.