NaSH in the construction of thiophene ring fused with N-heterocycles: a rapid and inexpensive synthesis of novel small molecules as potential inducers of apoptosis

Synthesis of raloxifene-like quinoxaline derivatives by intramolecular electrophilic cyclization with disulfides

The intramolecular electrophilic cyclization of alkynes with disulfides to form thieno[2,3-b]quinoxaline structures and to introduce thioether substituents afforded quinoxaline derivatives (7a-7d, 8a-8d). Among obtained eight derivatives, the raloxifene analogues (7c, 8b) showed specifically high cytotoxicity against breast cancer cells (SK-BR-3), and raloxifene analogues (8a) showed the highest cytotoxicity against human leukemia cells (HL-60). None of the raloxifene analogues (7a-7d, 8a-8d) showed cytotoxicity against human lung fibroblasts (WI-38), which are normal cells.

In silico assessment and sonochemical synthesis of 2-alkynyl 3-chloropyrazines as prospective ligands for SARS-CoV-2

The recent global pandemic caused by COVID-19 has triggered an intense effort worldwide towards the development of an effective cure for this disease. In our effort we have explored the 2-alkynyl substituted 3-chloropyrazine framework as a potential template for the design of molecules for this purpose. Our strategy was supported by the in silico studies of representative compounds to assess their binding affinities via docking into the N-terminal RNA-binding domain (NTD) of N-protein of SARS-CoV-2. Thus we created a small library of molecules based on the aforementioned template via an environmentally safer method that involved the rapid synthesis of 2-alkynyl 3-chloropyrazine derivatives under Cu-catalysis assisted by ultrasound. The reactions proceeded via the coupling of 2,3-dichloropyrazine with commercially available terminal alkynes in the presence of CuI, PPh₃ and K₂CO₃ in PEG-400. Further molecular modelling studies helped in establishing a virtual SAR (Structure Activity Relationship) within the series and identification of three potential hits. The desirable ADME was also predicted for these three molecules suggesting their prospective medicinal value.

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

A series of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines was synthesized for the first time by the reactions of chloroethynylphosphonates with unsubstituted and 5(6)-substituted 2-thiouracils. The reaction of chloroethynylphosphonates with 6-substituted 2-thiouracils bearing electron-donor groups (CH₃, Ph) proceeded with high regioselectivity involving the cyclization through the N³-nitrogen atom to form new 3-phosphonylated thiazolo[3,2-a]-5-oxopyrimidines with good yield. In the case of unsubstituted and 5-methyl-2-thiouracils, cyclization occurred predominantly through the N¹ atom and partially via the N³-nitrogen atom to form a mixture of the corresponding thiazolo[3,2-a]-7- and 5-oxopyrimidines. A dramatic change in the reaction regioselectivity was observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio.

Regioselective synthesis of dipyrrolopyrazine (DPP) derivatives via metal free and metal catalyzed amination and investigation of their optical and thermal properties

Pyrazine is an important molecular scaffold employed in organic optoelectronic materials.

Efficient synthesis of 2-phenyl-3-substituted furo/thieno[2,3-b]quinoxalines via Sonogashira coupling reaction followed by iodocyclization and subsequent palladium-catalyzed cross-coupling reactions

In this paper, we report the successful synthesis of new 2-phenyl-3-substituted furo/thieno[2,3-b]quinoxaline derivatives from 2-chloro-3-methoxyquinoxaline and 2-chloro-3-(methylthio)quinoxaline by a three-step approach.

A Pd(ii)-catalyzed C–H activation approach to densely functionalized N-heteroaromatics related to neocryptolepine and their evaluation as potential inducers of apoptosis

Bioactive indoloquinolines are synthesized via Pd(ii)-catalyzed intramolecular oxidative C–H alkenylation as the key step.

A greener approach towards double heteroarylation of N, O and S nucleophiles: synthesis of bioactive polynuclear fused N-heteroarenes

We report first general and common strategy for double heteroarylation of N, O and S nucleophiles leading to polynuclear N-heteroarenes.