Modular access to sulfur substituted analogues of isocytosine via photoredox catalysis.

A photoredox approach for synthesizing sulfur-substituted analogues of isocytosine via coupling of modular phenyl propargyl chloride with thiourea has been reported. The resulting product with an amine group was found amenable to various late-stage modifications, providing access to a broad range of sulfur-containing isocytosine derivatives.

Visible-Light-Mediated Synthesis of Thioesters Using Thiocarboxylic Acid as the Dual Reagent.

We have developed a visible-light-driven method for thioester synthesis that relies on the unique dual role of thiobenzoic acids as one-electron reducing agents and reactants leading to the formation of sulfur radical species. This synthetic process offers a wide scope, accommodating various thioacid and thiol substrates without the need for a photocatalyst.

Visible-Light-Mediated Synthesis of N-Acyl-N,O-hemiacetals from Terminal Alkynes: Access to N,N-, N,S-, and N,O-Acetals.

A mild electron donor-acceptor complex-mediated approach for the synthesis of N-acyl-N,O-hemiacetals has been reported. The key feature of this protocol is that it allows for direct access to electrophilic N-acylimines at room temperature without prefunctionalization of the hydroxyl group. The in situ generated N-acylimine can react with different nucleophiles, viz., alcohols, thiols, and nitriles, to afford a diverse range of scaffolds such as N,O-, N,S-, and N,N-acetals.

Metal-Free Tunable 1,2-Difunctionalization of Terminal Alkynes: Synthesis of ß-Substituted α,ß-Unsaturated Ketones.

A metal-free tunable 1,2-difunctionalization of the terminal alkynes showcasing a tandem installation of C-C and C-S bonds has been developed. The key enabling factor for the approach is the use of acetic acid as an acyl source to synthesize ß-substituted α,ß-unsaturated ketones. The reaction at room temperature leads to the regioselective acylation at the terminal carbon of alkynes, whereas at -78 °C, the acylation occurs at the more substituted carbon.

Studies towards investigation of Naphthoquinone-based scaffold with crystal structure as lead for SARS-CoV-19 management.

In this work, 1-(4-bromophenyl)-2a,8a-dihydrocyclobuta[b]naphthalene-3,8­dione (1-(4-BP)DHCBN-3,8-D) has been characterized by single crystal X-ray to get it's crystal structure with R(all data) - R1 = 0.0569, wR2 = 0.0824, 13C and 1HNMR, as well as UV-Vis and IR spectroscopy. Quantum chemical calculations via DFT were used to predict the compound structural, electronic, and vibrational properties. The molecular geometry of 1-(4-BP)DHCBN-3,8-Dwas optimized utilizing the B3LYP functional at the 6-311++G(d,p) level of theory. The Infrared spectrum has been recorded in the range of 4000-550 cm-1. The Potential Energy Distribution (PED) assignments of the vibrational modes were used to determine the geometrical dimensions, energies, and wavenumbers, and to assign basic vibrations. The UV-Vis spectra of the titled compound were recorded in the range of 200-800 nm in ACN and DMSO solvents. Additionally, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap and electronic transitions were determined using TD-DFT calculations, which also simulate the UV-Vis absorption spectrum. Natural Bond Orbital (NBO) analysis can be used to investigate electronic interactions and transfer reactions between donor and acceptor molecules. Temperature-dependent thermodynamic properties were also calculated. To identify the interactions in the crystal structure, Hirshfeld Surface Analysis was also assessed. The Molecular Electrostatic Potential (MEP) and Fukui functions were used to determine the nucleophilic and electrophilic sites. Additionally, the biological activities of 1-(4-BP)DHCBN-3,8-D were done using molecular docking. These results demonstrate a significant therapeutic potential for 1-(4-BP)DHCBN-3,8-D in the management of Covid-19 disorders. Molecular Dynamics Simulation was used to look at the stability of biomolecules.

Photoredox-Promoted Selective Synthesis of C-5 Thiolated 2-Aminothiazoles from Terminal Alkynes.

A mild photoredox approach enabling the first one-step synthesis of thiolated 2-aminothiazoles has been reported. Notably, the incorporation of thio group on electron-rich heteroarenes such as aminothiazoles via conventional nucleophilic aromatic substitution (SNAr) presents a significant challenge owing to polarity mismatch. Herein, we present a remarkable site-selective installation of thio group at the C-5 position of the electron-rich aminothiazole skeleton and successfully used them for the postfunctionalization of drugs and natural products.

Photoredox Catalyzed Thioformylation of Terminal Alkynes Using Nitromethane as a Formyl Source.

A photoredox thioformylation of terminal alkynes using nitromethane as a formyl anion equivalent, thereby leading to the synthesis of (E)-1,2-difunctionalized acrylaldehyde, has been described. The current strategy introduces an adaptable aldehyde function across an alkyne and offers a new route to synthesizing α-alkyl/aryl aldehydes.

Synthesis of 1,2-oxazetidines with a free -NH group via photoredox catalysis.

A photoredox approach enabling one-step synthesis of oxazetidines with a free -NH group via the combined use of alkyne, thiophenol, and azide has been reported. The synthesized oxazetidine with the free -NH group was stable enough for various late-stage transformations such as methylation, acetylation, tosylation, and ring-opening reaction to afford synthetically useful α-aminoketones.