In Silico Biological Profile Prediction of Some Selectively Synthesized Acyl Rhamnopyranosides

Over the past several decades significant biological activities including brains protective and antimicrobial activities have made sugar esters (SEs) as a topic of great interest. In this context, unimolar 3-chlorobenzoylation of methyl α-L-rhamnopyranoside (4) using dibutyltin oxide method regioselectively furnished only the 3-O-substitution product 5 in excellent yield. The reaction proceeded via the formation of a cyclic 2,3-O-dibutylstannylene intermediate where equatorial hydroxyl group is activated by the tin atom leading to the formation of product 5 only. To get biologically important rhamnopyranoside esters chlorobenzoate 5 was further converted into three newer 2,4-di-O-acyl products 6-9 with other acylating agents using direct acylation method. Prediction of activity spectra for substances (PASS) indicated that these rhamnopyranoside esters have many promising biological profiles including CYP2H substrate, membrane permeability inhibitor and better antifungal activities. Additionally, ADMET and drug likeness properties of SEs 5-8 were predicted and discussed.

Benzylic C−H acylation by cooperative NHC and photoredox catalysis

Methods that enable site selective acylation of sp3 C-H bonds in complex organic molecules are not well explored, particularly if compared with analogous transformations of aromatic and vinylic sp2 C-H bonds. We report herein a direct acylation of benzylic C-H bonds by merging N-heterocyclic carbene (NHC) and photoredox catalysis. The method allows the preparation of a diverse range of benzylic ketones with good functional group tolerance under mild conditions. The reaction can be used to install acyl groups on highly functionalized natural product derived compounds and the C-H functionalization works with excellent site selectivity. The combination of NHC and photoredox catalysis offers options in preparing benzyl aryl ketones.

Synthesis, Characterization, and Molecular Docking Against a Receptor Protein FimH of Escherichia coli (4XO8) of Thymidine Derivatives

Thymidine is known as a progenitor of nucleosides that have significant biological activity. The widening importance of nucleoside derivatives as unrivaled potential antimicrobial and therapeutic agents has attracted contemplation to the synthesis of thymidine derivatives. In the present study, thymidine was treated with various acyl halides to produce 5ʹ-O-acyl thymidine derivatives by direct acylation method with an excellent yield. To obtain newer products for antimicrobial assessment studies, the 5ʹ-O-thymidine derivatives were further modified into three series of 3ʹ-O-acyl thymidine derivatives containing a wide variety of functionalities in a single molecular framework. The chemical structures of the newly synthesized compounds were elucidated by analyzing their physicochemical, elemental, and spectroscopic data. Additionally, the X-ray powder diffraction (XRD) of these acylated products was studied. For the computational investigation, we have selected eight synthesized thymidine derivatives, which have notable antibacterial activity, and performed molecular docking against bacterial lectin protein FimH of Escherichia coli (4XO8) to suggest a potent inhibitor against bacterial function. Molecular docking was performed using AutoDock Vina to calculate the binding affinities and interactions between the antibacterials and the FimH E. coli (4XO8). It was found that the selected thymidine derivatives have strongly interacted mainly with Tyr48, Tyr137, Asp140, Arg98, Gln133, Phe1, Asn23, Asn135, Lys76, Asp47, Ile13, and Ile52 residues. In silico pharmacokinetic properties were also predicted to search their absorption, metabolism, excretion, and toxicity. This computational examination showed that these thymidine derivatives might be used as potential inhibitors against the promising antibacterial activity for future studies. Resumen. Se prepararon varios derivados 5ʹ-O-acil timidínicos por acilación directa con rendimientos excelentes que fueron transformados en tres series de derivados 3ʹ-O-acil timidínicos con una amplia variedad de funcionalidades. Estos compuestos fueron la base de un estudio de docking dirigido a la lectina bacteriana FimH de Escherichia coli (4XO8) con la finalidad de proponer un inhibidor contra esta función bacteriana.

Nickel-Catalyzed Electrochemical Reductive Relay Cross-Coupling of Alkyl Halides with Alkyl Carboxylic Acids

A highly regioselective Ni-catalyzed electrochemical (undivided cell) reductive relay cross-coupling between alkyl carbox-ylic acids and alkyl bromides has been developed. This strategy allows the direct acylation of benzylic C(sp3)–H bonds...

Ribose Moieties Acylation and Characterization of Some Cytidine Analogs

Modification of naturally occurring nucleosides is an important area in the search for new agents with therapeutic potential. In this study, nucleoside molecules, that is, cytidine analogs bearing ribose moieties were successfully synthesized to obtain 5´-O-acyl cytidine (2), which in turn was converted into 2´,3´-di-O-acyl cytidine (3–7) through direct acylation. Similarly, several cytidine analogs (8–15) were formed using the aforementioned technique. Physicochemical properties and spectroscopic methods were used to characterize the newly synthesized cytidine analogs. X-ray powder diffraction was employed for quantitatively identifying crystalline compounds. Hence, these synthesized derivatives can be used as potential antimicrobial agents and promising drug candidates

N-[3,5-Bis(trifluoromethyl)phenyl]-5-bromo-2-hydroxybenzamide Analogues: Novel Acetyl- and Butyrylcholinesterase Inhibitors

Background: Development of acetyl- (AChE) and butyrylcholinesterase (BuChE) inhibitors belongs to viable strategies for the treatment of dementia and other diseases related to decrease in cholinergic neurotransmission. Objective: That is why we designed twenty-two analogues of a dual AChEBuChE salicylanilide inhibitor, N-[3,5-bis(trifluoromethyl)phenyl]-5-bromo-2-hydroxybenzamide 1, to improve its potency. Methods: We prepared N,N-disubstituted (thio)carbamates via direct acylation with (thio)carbamoyl chloride, N-n-alkyl monosubstituted carbamates using isocyanates as well as its salicylanilide core analogues. The derivatives were evaluated in vitro against AChE from electric eel and BuChE from equine serum using spectrophotometric Ellman’s method. Results: The compounds showed moderate inhibition of both AChE and BuChE with IC50 from 18.2 to 196.6 μmol.L-1 and 9.2 to 196.2 μmol.L-1, respectively. Importantly, based on the substitution pattern, it is possible to modulate selectivity against AChE or BuChE and some derivatives also produced a balanced inhibition. In general, the most promising analogues were N-alkyl (C2-C6) carbamates and isomers with a changed position of phenolic hydroxyl. N-[3,5-Bis(trifluoromethyl)phenyl]-3-bromo-5- hydroxybenzamide 4a was the best inhibitor of both cholinesterases. Conclusion: A wide range of the derivatives improved the activity of the hit 1, they were superior to carbamate drug rivastigmine against AChE and some of them also against BuChE. The most promising derivatives also fit physicochemical space and structural features for CNS drugs together with an escalated lipophilicity.

Aldehydes: magnificent acyl equivalents for direct acylation

This review sheds light on the use of aldehydes in the selective acylation of arene, heteroarene and alkyl (sp3, sp2 and sp) C–H bonds by proficient utilization of the C–H activation strategy.