Synthesis, structure and antibacterial activity of new 2-(1-(2-(substituted-phenyl)-5-methyloxazol-4-yl)-3-(2-substitued-phenyl)-4,5-dihydro-1H-pyrazol-5-yl)-7-substitued-1,2,3,4-tetrahydroisoquinoline derivatives

Synthesis of biologically important tetrahydroisoquinoline (THIQ) motifs using quantum dot photocatalyst and evaluation of their anti-bacterial activity

Our study introduces an efficient photocatalytic approach for synthesizing biologically significant C1-substituted tetrahydroisoquinoline (THIQ) motifs, employing WS2 quantum dots (QDs) as catalysts. This method enables the formation of C-C and C-P bonds at the C1 position of the THIQ motif. The resulting compounds exhibit substantial antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) bacteria, with low minimum inhibitory concentration (MIC) values. Notably, the WS2 QD catalyst demonstrates recyclability and suitability for gram-scale reactions, underscoring the sustainability and scalability of our approach. Overall, our research presents a versatile and cost-effective strategy for synthesizing C1-substituted THIQ derivatives, highlighting their potential as novel therapeutic agents in biology and medicinal chemistry.

Iron Trichloride-Mediated Cascade Reaction of Aminosugar Derivatives for the Synthesis of Fused Tetrahydroisoquinoline-Tetrahydrofuran Systems

A method to obtain tetrahydroisoquinolines (THIQs) fused to tetrahydrofuran rings from aminosugar derivatives has been developed. The procedure relies on a key deprotection of benzyl ethers followed by a double-cyclization sequence, using FeCl₃ as the sole reagent. This tandem reaction affords the construction of novel fused polycyclic heterocycles with total stereochemical control.

1,2,3,4-Tetrahydroisoquinoline (THIQ) as privileged scaffold for anticancer de novo drug design

Introduction: Cancer is a dreadful disorder that is emerging as one of the leading causes of mortality across the globe. The complex tumor environment, supplemented with drawbacks of the existing drugs, has made it a global health concern. The Tetrahydroisoquinoline (THIQ) ring holds an important position in medicinal chemistry due to its wide range of pharmacological properties. Several THIQ based natural products have been previously explored for their antitumor properties, making it a vital scaffold for anticancer drug design.Areas covered: This review article addresses the potential of THIQ as anticancer agents. Various medicinal chemistry strategies employed for the design and development of THIQ analogs as inhibitors or modulators of relevant anticancer targets have been discussed in detail. Moreover, the common strategies employed for the synthesis of the core scaffold are also highlighted.Expert opinion: Evidently, THIQs have tremendous potential in anticancer drug design. Some of these analogs exhibited potent activity against various cancer molecular targets. However, there are some drawbacks, such as selectivity that need addressing. The synthetic ease for constructing the core scaffold complimented with its reactivity makes it ideal for further structure-activity relationship studies. For these reasons, THIQ is a privileged scaffold for the design and development of novel anticancer agents.

Medicinal chemistry perspectives of 1,2,3,4-tetrahydroisoquinoline analogs - biological activities and SAR studies

Isoquinoline alkaloids are a large group of natural products in which 1,2,3,4-tetrahydroisoquinolines (THIQ) form an important class. THIQ based natural and synthetic compounds exert diverse biological activities against various infective pathogens and neurodegenerative disorders. Due to these reasons, the THIQ heterocyclic scaffold has garnered a lot of attention in the scientific community which has resulted in the development of novel THIQ analogs with potent biological activity. The present review provides a much-needed update on the biological potential of THIQ analogs, their structural-activity relationship (SAR), and their mechanism of action. In addition, a note on commonly used synthetic strategies for constructing the core scaffold has also been discussed.

Molecular docking, molecular modeling, vibrational and biological studies of some new heterocyclic α-aminophosphonates

A new diphenyl (aryl) (Ǹ-quinazolin-4-yl-hydrazino) methylphosphonates 3a-3d was synthesized via anhydrous zinc chloride catalyzed Kabachnic-Fields reaction. The structure of the synthesized compounds was confirmed by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, ³¹P NMR and MS spectral data. The synthesized compounds showed significant antimicrobial and also remarkable cytotoxicity anticancer activities against breast carcinoma cell line (MCF7). The quantum chemical calculations were performed using density functional theory (DFT) to study the effect of the changes of molecular and electronic structures on the biological activity of the investigated compounds. Also, NBO and theoretical FT-IR were calculated. The experimental results were validated by molecular docking simulation of compound 3b in the active pocket of the enzyme. The important binding interactions with the key residues in the active site were revealed. A good correlation was found between the quantum chemical parameters and experimental data.

De-novo design, synthesis and evaluation of novel 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives as HIV-1 reverse transcriptase inhibitors

Background

Acquired Immune Deficiency Syndrome (AIDS) is the advanced stage of infection caused by Human Immunodeficiency Virus (HIV). HIV/AIDS had a great impact on society, both as an illness and as a source of discrimination. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) are structurally diverse group of compounds which binds to Reverse Transcriptase (RT) enzyme of HIV. Like other anti-HIV drugs, long-term clinical effectiveness of approved NNRTIs has been hampered due to the rapid development of drug resistance. So, there is an urgent need to discover the NNRTIs, which can be effective against the drug sensitive as well as drug resistant strains of HIV-1 RT.

Results

Two series of novel thirty, 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline analogues (5a-o) and (8a-o) were designed and synthesized as inhibitor of HIV-1 reverse transcriptase. All the synthesized compounds were characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, mass spectroscopy and evaluated for in-vitro RT inhibitory activity. Among the tested compounds, eighteen compounds exhibited more than 50 % inhibition at tested 100 μM concentration, in which two compounds 8h and 8l showed promising inhibition (74.82 and 72.58 %) respectively. The preliminary structure–activity relationship (SAR) of the test compounds and docking studies of the two significantly active compounds 8h and 8l were performed to examine their putative binding with HIV-RT. Predicted physiochemical parameters of the synthesized compounds were within the acceptable range of drugable properties.

Conclusion

The results obtained from this investigation revealed that, the synthesized compounds (5a-o) and (8a-o) showed moderate to promising HIV-1 RT inhibition activity. The overall SAR studies can help in identification of further lead as well as in designing of newer potential inhibitor of HIV-1 RT.

Graphical Abstract

A novel methodology for synthesis of dihydropyrazole derivatives as potential anticancer agents

A flexible and efficient method for the synthesis of 4,5-dihydropyrazole derivatives has been developed.

Synthesis, structure and antibacterial activity of potent DNA gyrase inhibitors: N'-benzoyl-3-(4-bromophenyl)-1H-pyrazole-5-carbohydrazide derivatives

A total of 19 novel (3a-3s) N'-benzoyl-3-(4-bromophenyl)-1H-pyrazole-5-carbohydrazide analogs were designed, synthesized, and evaluated for biological activities as potential DNA gyrase inhibitors. The results showed that compound 3k can strongly inhibit Staphylococcus aureus DNA gyrase and Bacillus subtilis DNA gyrase (with IC50 of 0.15 µg/mL and 0.25 µg/mL, respectively). Structure-activity relationships were also discussed base on the biological and docking simulation results.

Rapid synthesis and antiviral activity of (quinazolin-4-ylamino)methyl-phosphonates through microwave irradiation

This study describes the simple synthesis of new (quinazolin-4-ylamino) methylphosphonates via microwave irradiation. Substituted-2-aminobenzonitrile reacted with 1,1-dimethoxy-N,N-dimethylmethanamine at a reflux condition to obtain N'-(substituted-2-cyanophenyl)-N,N-dimethylformamidine (1). The subsequent reaction of this intermediate product with α-aminophosphonate (2) in a solution containing glacial acetic acid in 2-propanol through microwave irradiation resulted in the formation of (quinazolin-4-ylamino)methyl-phosphonate derivatives 3a to 3x, which were unequivocally characterized by the spectral data and elemental analysis. The influence of the reaction conditions on the yield of 3a was investigated to optimize the synthetic conditions. The relative optimal conditions for the synthesis of 3a include a 1:1 molar ratio of N'-(2-cyanophenyl)-N,N-dimethylformamidine to diethyl amino(phenyl)methylphosphonate and a 4:1 volume ratio of isopropanol to HOAc in the solvent mixture, at a reaction temperature of 150 °C, with a microwave power of 100 W and a corresponding pressure of 150 psi for 20 min in the microwave synthesizer. The yield of 3a was approximately 79%, whereas those of 3b to 3x were approximately 77% to 86%. Some of the synthesized compounds displayed weak to good anti-Tobacco mosaic virus (TMV) activity.

2-(4-Bromophenyl)-3,4-dihydroisoquinolin-2-ium thiocyanate hemihydrate

In the title hemihydrated salt, C₁₅H₁₃BrN⁺·NCS⁻·0.5H₂O, the two benzene rings are aligned at a dihedral angle of 46.9 (1)°. The six-membered heterocycle of the dihydro­isoquinoline unit adopts a half-chair conformation. The water mol­ecule and thio­cyanate ion are linked by O—H⋯N hydrogen bonds, generating a four-membered ring motif. In addition, C—H⋯O and C—H⋯S inter­actions link the components into a chain along the c axis. π–π inter­actions [centroid–centroid distance = 3.974 (2) Å] link the chains into sheets and further π—π [centroid–centroid distance = 3.746 (2) Å] and C—H⋯π inter­actions give rise to a three-dimensional nework.

2-(2-Hy-droxy-phen-yl)-3,4-dihydro-iso-quinolin-1(2H)-one

There are two independent mol-ecules in the asymmetric unit of the title compound, C(15)H(13)NO(2), in both the six-membered dihydro-pyridine rings adopt a half-chair conformation. The two benzene rings make dihedral angles of 43.66 (10) and 62.22 (10)° in the two mol-ecules. In the crystal, the two independent mol-ecules are linked alternately by inter-molecular O-H⋯O hydrogen bonds, forming a zigzag chain along the c axis. Furthermore, inter-molecular C-H⋯π inter-actions link the chains into a three-dimensional network.

2-(2-Iodophenyl)-1,2,3,4-tetrahydroisoquinoline-1-carbonitrile

In the title compound, C₁₆H₁₃IN₂, the two benzene rings make a dihedral angle of 67.26 (5)°. The six-membered heterocycle of the tetra­hydro­isoquinoline unit adopts a half-chair conformation. In the crystal, adjacent mol­ecules are linked by pairs of weak inter­molecular C—H⋯N hydrogen bonds, forming inversion dimers. An intra­molecular C—H⋯I close contact is also observed.

Synthesis and antimicrobial activities of pyrano[3,2-c]quinoline, pyrimido [5′,4′:5,6]pyrano[3,2-c]quinoline and [1,2,4]triazolo[2″,3″:1′,6′]pyrimido [5′,4′:5,6]pyrano[3,2-c]quinoline derivatives

The synthesis of novel 7-(4-chlorophenyl)-6-hydroxy-3-methoxy-10-methyl-8,9-dihydro-7 H-pyrimido[5′, 4′: 5, 6]pyrano-[3,2- c]quinoline and [1,2,4]triazolo[2″,3″: 1′, 6′]pyrimido[5′, 4′: 5,6]pyrano[3,2- c]quinoline derivatives has been reported. The key intermediate 2-amino-4-(4-chlorophenyl)-5-hydroxy-8-methoxy-4H-pyrano[3, 2- c]-quinoline-3-carbonitrile was obtained by treating 4-hydroxy-7-methoxyquinolin-2(1 H)-one with various substituted α-cyanocinnamonitrile in ethanolic piperidine solution. Antimicrobial activity was shown for most of the synthesised compounds.