Carbazole-thiophene based fluorescent probe for selective detection of Cu2+ and its live cell imaging.

Highly sensitive and specific imaging of copper ion (Cu2+) in living cells is essential for better understanding the physiological and metabolic processes. We develop a novel fluorescent probe based on carbazole-thiophene for specific Cu2+ detection in living cells. Job's plot and density functional theory (DFT) confirmed a stoichiometric ratio of 2:1 between the probe molecules and Cu2+. This probe exhibits strong fluorescence in aqueous media, while its fluorescence intensity significantly decreased in the presence of Cu2+. An in vitro assay shows that the fluorescent probe has rapid response within 5 s and high sensitivity for the detection of Cu2+ in the range from 1 to 10 µM with a detection limit of 0.29 µM. Live cell studies reveal that the fluorescent probe has good cell-membrane permeability and can successfully visualize the fluctuation of the intracellular Cu2+ concentration. In addition, the fluorescent probe has low cytotoxicity, which may provide a new tool for monitoring other analytes in living cells.

CuBr/NHPI co-catalyzed aerobic oxidative [3 + 2] cycloaddition-aromatization to access 5,6-dihydro-pyrrolo[2,1-a]isoquinolines.

An efficient and enviromentally friendly CuBr/NHPI co-catalyzed aerobic oxidative [3 + 2] cycloaddition-aromatization cascade was realized with N-substituted tetrahydroisoquinolines and electron-deficient olefins. Under the mild conditions, the reaction proceeded smoothly and displayed excellent functional group tolerance, affording 5,6-dihydro-pyrrolo[2,1-a]isoquinolines in good to high yields. This protocol exhibits a broad substrate scope to both N-alkyl tetrahydroisoquinolines and dipolarophile substrates.

Diastereo- and enantioselective Aza-MBH-type reaction of nitroalkenes to N-tosylimines catalyzed by bifunctional organocatalysts.

The first example of diastereo- and enantioselective aza-MBH-type reaction was accomplished by the asymmetric synthesis of beta-nitro-gamma-enamines via a (1R,2R)-diaminocyclohexane thiourea derivative mediated tandem Michael addition and aza-Henry reaction in good yields (up to 95%) and high enantioselectivities (up to 91% ee) and diastereoselectivities (up to 1:99 dr).