Enantioselective synthesis of 8-azabicyclo[3.2.1]octanes via asymmetric 1,3-dipolar cycloadditions of cyclic azomethine ylides using a dual catalytic system.

The first example of asymmetric 1,3-dipolar cycloadditions between diazo imine-derived cyclic azomethine ylides and acryloylpyrazolidinone using a rhodium(ii) complex/chiral Lewis acid binary system is reported. The asymmetric cycloadditions afforded optically active 8-oxabicyclo[3.2.1]octanes with high diastereo- and enantioselectivities (up to >99 : 1 dr, 99% ee). A switch of exo/endo-selectivity was observed depending on the diazo substrates.

Synthesis of CdSe Quantum Dots Using Fusarium oxysporum.

CdSe quantum dots are often used in industry as fluorescent materials. In this study, CdSe quantum dots were synthesized using Fusarium oxysporum. The cadmium and selenium concentration, pH, and temperature for the culture of F. oxysporum (Fusarium oxysporum) were optimized for the synthesis, and the CdSe quantum dots obtained from the mycelial cells of F. oxysporum were observed by transmission electron microscopy. Ultra-thin sections of F. oxysporum showed that the CdSe quantum dots were precipitated in the intracellular space, indicating that cadmium and selenium ions were incorporated into the cell and that the quantum dots were synthesized with intracellular metabolites. To reveal differences in F. oxysporum metabolism, cell extracts of F. oxysporum, before and after CdSe synthesis, were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results suggested that the amount of superoxide dismutase (SOD) decreased after CdSe synthesis. Fluorescence microscopy revealed that cytoplasmic superoxide increased significantly after CdSe synthesis. The accumulation of superoxide may increase the expression of various metabolites that play a role in reducing Se4+ to Se2- and inhibit the aggregation of CdSe to make nanoparticles.