This study presents a visible-light-promoted regioselective C–H selenylation method for the synthesis of selenylated pyrazolo[1,5-a]pyrimidines. The researchers employed erythrosine B as a photocatalyst and optimized the reaction conditions to achieve high yields. The methodology demonstrated broad substrate scope and regioselectivity, and gram-scale synthesis was also feasible.
- Visible-light-promoted C–H functionalization is an attractive strategy for direct conversion of C–H bonds to C–C and C–heteroatom bonds.
- Organoselenides are useful organic molecules with applications in pharmaceuticals, catalysis, and material science.
- The synthesis of organoselenides through C–H functionalization is an important strategy.
- Pyrazolo[1,5-a]pyrimidine derivatives are nitrogen-containing fused heterocycles found in various biologically and pharmaceutically important molecules.
- Synthesis of functionalized pyrazolo[1,5-a]pyrimidine derivatives has attracted synthetic chemists.
- Previous methodologies for the synthesis of pyrazolo[1,5-a]pyrimidines did not extensively explore selenylation of the scaffold.
- Erythrosine B is an organic dye with less explored photocatalytic applications compared to other dyes.
- Researchers developed a visible-light-promoted C–H selenylation method using erythrosine B as the photocatalyst.
- Optimization of reaction conditions led to the use of MeOH as the solvent, 3 mol % erythrosine B as the photocatalyst, and an oxygen atmosphere under white LED irradiation.
- The methodology demonstrated high efficiency and regioselectivity in the selenylation of various pyrazolo[1,5-a]pyrimidine derivatives and diselenides.
- The protocol was also applicable for the selenylation of other electron-rich heterocycles.
- Gram-scale synthesis of selenylated pyrazolo[1,5-a]pyrimidines was successfully achieved.
Visible-light-promoted C–H selenylation is a valuable strategy for the direct synthesis of selenylated pyrazolo[1,5-a]pyrimidines. In this study, the researchers utilized erythrosine B as a photocatalyst and optimized the reaction conditions to achieve efficient selenylation at the 3-position of pyrazolo[1,5-a]pyrimidine derivatives. The use of a white LED as the light source allowed for the regioselective formation of selenylated products. The methodology demonstrated a broad substrate scope, including various pyrazolo[1,5-a]pyrimidine derivatives with different substituents and electron-rich heterocycles. The yields were generally good to excellent. Additionally, the researchers successfully performed gram-scale synthesis, showcasing the practical applicability of the method. Controlled experiments using radical scavengers suggested a radical-mediated mechanistic pathway for the transformation.
The authors aimed to develop a methodology for the extensive selenylation of pyrazolo[1,5-a]pyrimidines, an important scaffold for various biologically active and pharmaceutically important molecules. They utilized visible-light photocatalysis with erythrosine B as the photocatalyst under white LED irradiation. The optimized conditions involved MeOH as the solvent, 3 mol % erythrosine B as the photocatalyst, and an oxygen atmosphere. The methodology exhibited good yields and high regioselectivity for various pyrazolo[1,5-a]pyrimidine derivatives and different diselenides. The authors also demonstrated the gram-scale synthesis of the selenylated products. Controlled experiments indicated that the reaction proceeded via a radical pathway. This work expands the scope of visible-light-promoted C–H functionalization and provides a useful strategy for the synthesis of selenylated pyrazolo[1,5-a]pyrimidines.
In this study, the researchers focused on the development of a visible-light-enabled methodology for C–H selenylation, aiming to synthesize organoselenides efficiently. Pyrazolo[1,5-a]pyrimidine derivatives were chosen as the target scaffold due to their importance in various biological and pharmaceutically relevant molecules.
Overall, this study provides an efficient and regioselective approach for the synthesis of selenylated pyrazolo[1,5-a]pyrimidines using visible-light photocatalysis.