Diastereodivergent Synthesis of α-Chiral Tertiary Azides through Catalytic Asymmetric Michael Addition.

A diastereodivergent synthesis of α-chiral tertiary azides through catalytic enantioselective Michael addition of α-azido indanones to β,γ-unsaturated α-ketoesters is described. The merger of a newly designed bifunctional phosphoramide and hexafluoroisopropanol (HFIP) affords -adducts, whereas the use of thiourea provides -adducts without the aid of HFIP. Notably, additive HFIP proves to be the key control element to achieve diastereoselectivity reversal in the former case.

H-bond donor-directed switching of diastereoselectivity in the Michael addition of α-azido ketones to nitroolefins.

The development of catalyst-controlled stereodivergent asymmetric catalysis is important for providing facile access to all stereoisomers of chiral products with multiple stereocenters from the same starting materials. Despite progress, new design strategies for diastereodivergent asymmetric catalysis are still highly desirable. Here we report the potency of H-bond donors as the governing factor to tune diastereoselectivity in a highly diastereoselective switchable enantioselective Michael addition of α-azido ketones to nitroolefins.

A Rhodamine-Benzimidazole Based Chemosensor for Fe(3+) and its Application in Living Cells.

A rhodamine-benzimidazole based chemosensor was designed and prepared for Fe(3+) via opening of the spiro-ring to give fluorescent and colored species. L exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Fe(3+) in aqueous solution with comparatively wide pH range (5.8-7.

A highly selective and sensitive probe for Cu2+ based on rhodamine-pyridazine conjugate and its application.

A naked-eye fluorescent chemodosimeter based on rhodamine-pyridazine conjugate L was synthesized and characterized. L exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Cu(2+) in aqueous solution with a broad pH span (1-10). The detection limit of the probe was shown to be up to 0.

A fluorescence ratiometric chemosensor for Fe³⁺ based on TBET and its application in living cells.

Based on a through bond energy transfer (TBET) between rhodamine and naphthalimide fluorophores, a fluorescent ratiometric chemosensor L was designed and prepared for highly selective detection of Fe(3+) in aqueous solution and in living EC109 cells. These significant changes in the fluorescence color could be used for naked-eye detection. The reversibility established the potential of the probe as chemosensor for Fe(3+) detection.

A novel colorimetric and off-on fluorescent chemosensor for cr(3+) in aqueous solution and its application in live cell imaging.

A novel colorimetric and off-on fluorescent chemosensor 2 was designed and synthesized, which showed reversible and highly selective and sensitive recognition toward Cr(3+) over other examined metal ions in aqueous solution. Upon addition of Cr(3+), the solution of chemosensor 2 resulted in a color change from colorless to obvious pink color, these significant changes in color could be used for naked-eye detection. Chemosensor 2 exhibited a stable response for Cr(3+) in the range 0-10 μM with a detection limit of 1 ppm.