New HIV-1 reverse transcriptase inhibitors based on a tricyclic benzothiophene scaffold: Synthesis, resolution, and inhibitory activity

Configurationally stable dithia[7]helicene and dithia-quasi[8]circulene fused dithiolones

Stereochemically stable dithia[7]helicene and dithia-quasi[8]circulene decorated with 1,3-dithiol-2-one motifs were synthesized by simple and double oxidative dehydrocyclisation.

Rh(III)-Catalyzed Oxidative C-2 Coupling of N-Pyridinylindoles with Benzo[b]thiophene 1,1-Dioxides via C-H Bond Activation

An efficient Rh(III)-catalyzed cross-dehydrogenative coupling of N-pyridinylindoles with benzo[b]thiophene 1,1-dioxides has been developed through directing-group-assisted C-H activation. This transformation constructs a new C-C bond from two inert C-H bonds in a one-pot reaction. The present reaction is compatible with various functional groups with respect to indoles and benzothiophene[b] 1,1-dioxides. Furthermore, the emission properties of synthesized compounds have been explored.

Concise and Efficient Synthesis of Indole-Indolone Scaffolds through MeOTf-Induced Annulation of N-(2-Cyanoaryl)indoles

MeOTf-triggered annulation of N-(2-cyanoaryl)indoles to provide indolo[1,2-a]indol-10-imines and the corresponding indolo[1,2-a]indol-10-ones have been described under metal-free conditions. A variety of functional groups are tolerated in their scaffolds with good to excellent yields. The reaction could be carried to gram scale.

Efficient synthesis of chiral 2,3-dihydro-benzo[b]thiophene 1,1-dioxides via Rh-catalyzed hydrogenation

Rh-catalyzed asymmetric hydrogenation of prochiral substituted benzo[b]thiophene 1,1-dioxides was successfully developed, affording various chiral 2,3-dihydrobenzo[b]thiophene 1,1-dioxides with high yields and excellent enantioselectivities (up to 99% yield and >99% ee). In particular, for challenging substrates, such as aryl substituted substrates with sterically hindered groups and alkyl substituted substrates, the reaction proceeded smoothly in our catalytic system with excellent results. The gram-scale asymmetric hydrogenation proceeded well with 99% yield and 99% ee in the presence of 0.02 mol% (S/C = 5000) catalyst loading. The possible hydrogen-bonding interaction between the substrate and the ligand may play an important role in achieving high reactivity and excellent enantioselectivity.

An overview of benzo[b]thiophene-based medicinal chemistry

Among sulfur containing heterocycles, benzothiophene and its derivatives are at the focus as these candidates have structural similarities with active compounds to develop new potent lead molecules in drug design. Benzo[b]thiophene scaffold is one of the privileged structures in drug discovery as this core exhibits various biological activities allowing them to act as anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant, anti-tubercular, anti-diabetic, anti-convulsant agents and many more. Further, numerous benzothiophene-based compounds as clinical drugs have been extensively used to treat various types of diseases with high therapeutic potency, which has led to their extensive developments. Due to the wide range of biological activities of benzothiophene, their structure activity relationships (SAR) have generated interest among medicinal chemists, and this has culminated in the discovery of several lead molecules against numerous diseases. The present review is endeavoring to highlight the progress in the various pharmacological activities of benzo[b]thiophene derivatives. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic benzothiophene-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes. Also, SAR studies that highlight the chemical groups responsible for evoking the potential activities of benzothiophene derivatives are studied and compared.

Enantioselective construction of tricyclic pyrrolidine-fused benzo[b]thiophene 1,1-dioxide derivatives via copper(i)-catalyzed asymmetric 1,3-dipolar cycloaddition

A facile Cu(i)-catalyzed asymmetric 1,3-dipolar cycloaddition is developed, affording chiral tricyclic pyrrolidine-fused benzo[b]thiophene derivatives in excellent diastereo- and enantioselectivities.

Selective binding and reverse transcription inhibition of single-strand poly(A) RNA by metal TMPyP complexes

Ni-, Cu-, and Zn-TMPyP are capable of binding to single-strand poly(A) RNA with high preference and affinity and inhibiting the reverse transcription of RNA by both M-MuLV and HIV-1 reverse transcriptase. With 10 nM azidothymidine, the IC50 value of M-TMPyP could be lowered to 10(-1) μM order.

Enzyme toolbox: novel enantiocomplementary imine reductases

Reducing reactions are among the most useful transformations for the generation of chiral compounds in the fine-chemical industry. Because of their exquisite selectivities, enzymatic approaches have emerged as the method of choice for the reduction of C=O and activated C=C bonds. However, stereoselective enzymatic reduction of C=N bonds is still in its infancy-it was only recently described after the discovery of enzymes capable of imine reduction. In our work, we increased the spectrum of imine-reducing enzymes by database analysis. By combining the currently available knowledge about the function of imine reductases with the experimentally uncharacterized diversity stored in protein sequence databases, three novel imine reductases with complementary enantiopreference were identified along with amino acids important for catalysis. Furthermore, their reducing capability was demonstrated by the reduction of the pharmaceutically relevant prochiral imine 2-methylpyrroline. These novel enzymes exhibited comparable to higher catalytic efficiencies than previously described enzymes, and their biosynthetic potential is highlighted by the full conversion of 2-methylpyrroline in whole cells with excellent selectivities.

Chiral resolution, absolute configuration assignment and biological activity of racemic diarylpyrimidine CH(OH)-DAPY as potent nonnucleoside HIV-1 reverse transcriptase inhibitors

(+)-3a and (-)-3a were successfully separated from racemate (±)-3a by the chiral technique of supercritical fluid chromatography (SCF) with enantiomeric excess (ee%) >99% and purity >99%, and assigned for their absolute configuration as R and S, respectively, by the experimental electronic circular dichroism (ECD) spectrum and simulated ECD spectra calculated by time-dependent density functional theory (TDDFT) calculations. (+)-(R)-3a displayed excellent activity with an EC(50) of 5.3 nM against wild-type HIV-1, which was 12-fold more potent than (-)-(S)-3a. However, (-)-(S)-3a showed higher potency than (+)-(R)-3a against the double HIV-1 RT mutant (K103N+Y181C) as well as HIV-2 strain ROD. The possible reason for the difference of (R)- and (S)-3a in anti-HIV-1 activity was interpreted by molecular docking.

HIV-1 NNRTIs: structural diversity, pharmacophore similarity, and implications for drug design

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) nowadays represent very potent and most promising anti-AIDS agents that specifically target the HIV-1 reverse transcriptase (RT). However, the effectiveness of NNRTI drugs can be hampered by rapid emergence of drug-resistant viruses and severe side effects upon long-term use. Therefore, there is an urgent need to develop novel, highly potent NNRTIs with broad spectrum antiviral activity and improved pharmacokinetic properties, and more efficient strategies that facilitate and shorten the drug discovery process would be extremely beneficial. Fortunately, the structural diversity of NNRTIs provided a wide space for novel lead discovery, and the pharmacophore similarity of NNRTIs gave valuable hints for lead discovery and optimization. More importantly, with the continued efforts in the development of computational tools and increased crystallographic information on RT/NNRTI complexes, structure-based approaches using a combination of traditional medicinal chemistry, structural biology, and computational chemistry are being used increasingly in the design of NNRTIs. First, this review covers two decades of research and development for various NNRTI families based on their chemical scaffolds, and then describes the structural similarity of NNRTIs. We have attempted to assemble a comprehensive overview of the general approaches in NNRTI lead discovery and optimization reported in the literature during the last decade. The successful applications of medicinal chemistry strategies, crystallography, and computational tools for designing novel NNRTIs are highlighted. Future directions for research are also outlined.