A regioselective [4 + 2] annulation approach to 5-acylindolizine-7-carbonitriles: generation of poly-substituted pyridines

Domino Approach to Heterocycles-Based Unsymmetrical Triarylmethanes through Heteroannulation of 2-(2-Enynyl)-pyridines with Enaminones

Herein, we report a copper-catalyzed protocol to access unsymmetrical triarylmethanes containing both indolizine and the chromone scaffolds in the same molecule via a 5-endo-dig cyclization of 2-(2-enynyl)-pyridines followed by reaction with 2-hydroxyaryl enaminones. A variety of 2-hydroxyaryl enaminones and 2-(2-enynyl)-pyridines were subjected to reaction under the optimal reaction conditions, and the respective triarylmethanes were obtained in good to excellent yields.

Catalyst-free assembly of a polyfunctionalized 1,2,4-triazole-fused N-heterocycle, 6-acylated pyrrolo[1,2-a][1,2,4]triazolo[5,1-c]pyrazine

A catalyst-free synthetic route to a new 1,2,4-triazole-pyrrolo[1,2-a]pyrazine hybrid system, 6-acylpyrrolo[1,2-a][1,2,4]triazolo[5,1-c]pyrazine, was realized upon sequential exposure of pyrrole-2-carbonitrile-derived substrates to DMF-DMA and acyl hydrazide through which acylated pyrazine and 1,2,4-triazole rings were consecutively formed with the formation of multiple bonds (one C-C bond and three C-N bonds). This annulative functionalization approach towards N-fused polycycles enabled us to install various substituents at specific positions on the core skeleton.

Generation of a poly-functionalized indolizine scaffold and its anticancer activity in pancreatic cancer cells

A highly efficient domino [4 + 2] annulation process was employed to construct a novel indolizine chemical scaffold. Biological investigation led us to identify 6w as a potent anticancer agent. 6w significantly inhibited cell viability in BxPC3 pancreatic cancer, MCF7 breast cancer, and PC3 prostate cancer cell lines with IC50 values of 0.47 ± 0.04, 1.82 ± 0.08 and 2.68 ± 0.08 µM, respectively. Remarkably, 6w showed a weak effect on cell viability of nontumorigenic human keratinocyte cell line HaCaT compared to the above three types of cancer cells. 6w most potently inhibited cell viability of BxPC3 cells, and 6w also potently reduced cell migration and induced apoptosis in BxPC3 cells through activation of caspase-3 and cleavage of PARP in a dose-dependent manner. These results suggest that 6w can be used for the development of potential anticancer drugs for the treatment of pancreatic cancer.

Base-promoted [4 + 2] annulation of pyrrole-2-carbaldehyde derivatives with β,γ-unsaturated α-ketoesters: syntheses of 5,6-dihydroindolizines

A base-promoted [4 + 2] annulation of pyrrole-2-carbaldehyde derivatives with β,γ-unsaturated α-ketoesters for the syntheses of multisubstituted 5,6-dihydroindolizines was developed.

Dioxygen-Triggered Oxosulfonylation/Sulfonylation of Terminal Olefins toward β-Keto Sulfones/Sulfones

A dioxygen-triggered oxosulfonylation/sulfonylation of unactivated olefins to achieve β-keto sulfones/sulfones has been developed. Interestingly, pluralistic mechanisms were found when different types of compounds were applied as substrates, and different products were achieved. The reaction is carried out with a high atomic efficiency in the absence of a metal and a catalyst at room temperature under an air atmosphere. Importantly, as a proof-of-concept, a bioactive molecule was synthesized on a gram-scale level using this method.