In
situ click chemistry has great potential for identifying enzyme
inhibitors. However, conventional in situ click chemistry provides
extremely low yields of the products, making it incompatible with
direct activity-based assays. Here, to address this issue, we focused
on the catalysis of azide–alkyne cycloaddition (AAC) by the
metal ion in metalloproteins. We chose 2-ethynyl N-heterocompounds as alkyne fragments which are activated by coordination
to the metal ion. For proof of concept, we applied metal ion-catalyzed
in situ AAC to identify inhibitors of Fe(II)-dependent lysine demethylase
5C (KDM5C). The triazole product was obtained in dramatically high
yield, dependently on Fe(II) in KDM5C, and the metalloprotein-catalyzed
click reaction was compatible with activity-based high-throughput
screening, enabling us to discover a potent KDM5C inhibitor. Thus,
metal-catalyzed in situ AAC should be generally applicable to other
metalloproteins.
Ph2P(O)-protected ethynes were successfully transformed to arylethynes in one-pot manner through t-BuOK-catalyzed deprotection followed by Sonogashira coupling with aryl halide. The arylethynes were obtained similarly by Ph2P(O)-deprotection, stannylation of the resulting terminal ethynes, and Migita-Kosugi-Stille coupling. Deprotection followed by intramolecular Eglinton coupling could be carried out in one-pot to provide cyclic butadiynes.
Asymmetric 1,4-addition reaction of arylboronic acid to cyclic enone was carried out in the presence of a chiral ferrocene-based phosphine ligand–palladium catalyst. The reaction of 2-cyclohexen-1-one by palladium complex with (S,Rp)-[1-(2-bromoferrocenyl)ethyl]diphenylphosphine afford a optically active β-arylcyclohexanone in good yield up to 71% ee.
Photoinduced charge separation processes of linear phenyleneethynylene derivatives (PEN) with different sequences of electron-withdrawing perfluorophenyl groups (A) and electron-donating phenyl groups (D) were investigated in an ionic liquid (IL), BmimTFSI, by picosecond time-resolved fluorescence (TRF) and transient absorption (TA) spectroscopies. Very rapid photoinduced charge separation within 10 ps in AADD was followed by the stabilization of the charge-transfer (CT) state by the solvation, while the excited states in ADAD and ADDA were ascribable to the locally excited (LE) state. Equilibrium between the LE and CT states was established for DAAD with time constants of forward and backward processes much faster than the solvation time. The relative population of the CT state increases with time owing to the dynamic stabilization of the CT state by the solvation. The elementary charge separation process, the increase in the CT population, and their relation to the solvation time were discussed.
A series of 9,10-anthrylene-substituted phenyleneethynylenes having Ph2N and CN groups were synthesized. A dye-sensitized solar cell fabricated by both Ph2N- and CN-substituted derivative exhibited the highest performance of photo-to-current energy conversion.
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