DMAP-catalyzed cascade reaction: one-pot synthesis of benzofurans in water

Construction of 3-Methyl-2-Substituted Benzo[b]furans and 3-Methyl-2-Substituted Benzo[b]thiophenes Using Solid Calcium Carbide as a Substitute for Gaseous Acetylene

A concise method for the facile construction of 3-methyl-2-substituted benzo[b]furans and 3-methyl-2-substituted benzo[b]thiophenes using low-cost, abundant, and easy-to-use solid calcium carbide instead of flammable and explosive gaseous acetylene as an original alkyne source, o-bromophenyl ethers or o-bromophenyl thioethers as substrates through an intramolecular carbanion-yne cyclization in a 5-exo-dig manner, and subsequent double-bond isomerization is described. The simultaneous formation of two C-C bonds is realized in a one-step route. The wide substrate scope, high yield, and simple workup manipulations are also merits of this method. The synthetic strategy can also be suitable for the gram scale.

Structure based designing of benzimidazole/benzoxazole derivatives as anti-leishmanial agents

Folates are essential biomolecules required to carry out many crucial processes in leishmania parasite. Dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase 1 (PTR1) involved in folate biosynthesis in leishmania have been established as suitable targets for development of chemotherapy against leishmaniasis. In the present study, various computational tools such as homology modelling, pharmacophore modelling, docking, molecular dynamics and molecular mechanics have been employed to design dual DHFR-TS and PTR1 inhibitors. Two designed molecules, i.e. 2-(4-((4-nitrobenzyl)oxy)phenyl)-1H-benzo[d]imidazole and 2-(4-((2,4-dichlorobenzyl)oxy)phenyl)-1H-benzo[d]oxazolemolecules were synthesized. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was performed to evaluate in vitro activity of molecules against promastigote form of Leishmania donovani using Miltefosine as standard. 2-(4-((4-nitrobenzyl)oxy)phenyl)-1H-benzo[d]imidazole and 2-(4-((2,4-dichlorobenzyl)oxy)phenyl)-1H-benzo[d]oxazolemolecules were found to be moderately active with showed IC₅₀ = 68 ± 2.8 µM and 57 ± 4.2 µM, respectively.

One-Pot Allylation-Intramolecular Vinylogous Michael Addition-Isomerization Cascade of o-Hydroxycinnamates and Congeners: Synthesis of Substituted Benzofuran Derivatives

A unique intramolecular vinylogous Michael addition leading to the synthesis of heterocycles has been disclosed. Base-promoted one-pot sequential O-allylation of o-hydroxy-cinnamates or -cinnamonitrile or -chalcones with γ-bromocrotonates followed by an intramolecular conjugate addition of vinylogous Michael donors resulted in the formation of highly substituted benzofuran derivatives in good to excellent yields. The intramolecular event followed by two [1,3]-H shifts leading to aromatization appears to be the key to the success of this unprecedented transformation.

Mechanochemical solid-state synthesis of 2-aminothiazoles, quinoxalines and benzoylbenzofurans from ketones by one-pot sequential acid- and base-mediated reactions

α-Chloroketones - obtained by the atom-economical chlorination of ketones with trichloroisocyanuric acid (TCCA) in the presence of p-TSA under ball-milling conditions - were set up for a sequential base-mediated condensation reaction with thiourea/thiosemicarbazides, o-phenylenediamine and salicylaldehyde to afford 2-aminothiazoles, 2-hydrazinylthiazoles, quinoxalines and benzoylbenzofurans, respectively, in respectable yields. The viability of one-pot sequential acid- and base-mediated reactions in the solid state under ball-milling conditions is thus demonstrated.

Synthesis and Bioactivity Evaluation of Novel 2-Salicyloylbenzofurans as Antibacterial Agents

In order to discover new antibacterial agents, series of 2-salicyloylbenzofuran derivatives were designed, synthesized and evaluated for their antibacterial activities against three Gram-(+) strains (methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 29213, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Streptococcus faecalis (S. faecalis) ATCC 29212) and one Gram-(-) strain (Escherichia coli (E. coli) ATCC 25922). The 2-salicyloylbenzofuran heterocycles were generated by Rap-Stoermer condensation of salicylaldehydes with phenacyl bromides and then converted to diverse O-ether derivatives by Williamson synthesis. The targeted products were screened for in vitro qualitative (zone of inhibition) and quantitative (MIC) antibacterial activities by agar well diffusion assay and agar dilution method. Amongst the compounds, those bearing carboxylic acid functional group were found to exhibit reasonable activity against Gram-(+) bacterial strains including S. faecalis, MSSA and MRSA with the most potent antibacterial agent 8h (MICs = 0.06-0.12 mM). Besides, the 2-salicyloylbenzofurans partly displayed inhibitory activity against MRSA with the best MICs = 0.14 mM (8f) and 0.12 mM (8h). Finally, the antibacterial results preliminarily suggested that the substituent bearing carboxylic acid group at salicyloyl-C2 and the bromine atoms on the benzofuran moiety seem to be the functionality necessary for antibacterial activities.

First Synthesis of 2-Ferrocenoyl-3-Methylbenzofuran Derivatives

The incorporation of the 3-methylbenzofuran moiety into the ferrocene nucleus leading to a series of structurally novel hybrids 2-ferrocenoyl-3-methylbenzofuran derivatives has been achieved in good yields of 76-85% through the one-pot Rap-Stoermer reaction of 1-chloroacetylferrocene with 2′-hydroxyacetophenones in refluxing CH3CN with the presence of K2CO3as base and PEG-400 as catalyst. These newly-synthesised compounds could be good candidates for the development of compounds for use in medicinal chemistry.

DMAP-promoted domino annulation of β-ketothioamides with internal alkynes: a highly regioselective access to functionalized 1,3-thiazolidin-4-ones at room temperature

One-pot DMAP-mediated regioselective access to functionalized 1,3-thiazolidin-4-ones has been achieved via annulation of β-ketothioamides with internal alkynes.

SnCl2/TiCl3-mediated deoximation of oximes in an aqueous solvent

A simple procedure for SnCl(2)/TiCl(3)-mediated deoximation of ketoximes in an aqueous solvent is reported. Under the conditions developed in this effort, various ketones and aldehydes are produced in good to excellent yields.

A novel and facile synthesis of 3-(2-benzofuroyl)- and 3,6-bis(2-benzofuroyl)carbazole derivatives

A facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a-k, 3,6-bis(2-benzofuroyl)carbazoles 5a-k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap-Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a-k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH(3)CN with the presence of PEG-400 as catalyst. The procedure offers easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.