Synthesis of Aryl Amine Derivatives from Benzyl Nitriles via Electrocyclization of in Situ Generated <i>N</i>‑Silyl Ketene Imines

The previously unexplored reactivity of <i>N</i>-silyl ketene imines in organic synthesis is reported. Benzyl nitriles containing an alkenyl or aryl group at the <i>ortho</i> position were smoothly converted into aryl amines in good yields under two sets of mild silylation conditions: (1) nonbasic conditions using TMSNTf₂–<i>i</i>Pr₂NEt or (2) basic anionic conditions using lithium diisopropylamide–triisopropylsilyl chloride (LDA–TIPSCl). The reaction probably proceeds via in situ generation of an <i>N</i>-silyl ketene imine followed by 6π-electrocyclization and aromatization

Enantioselective Total Synthesis of (+)-Iso-A82775C, a Proposed Biosynthetic Precursor of Chloropupukeananin

(+)-Iso-A82775C is a proposed biosynthetic precursor of the chloropupukeananin family and an important intermediate for related natural products. The first enantioselective total synthesis of (+)-iso-A82775C (18 steps, 2.2% overall yield) toward the eventual biomimetic total synthesis of chloropupukeananin is described. The key steps are (1) the enantioselective Diels–Alder reaction of 4-bromo-3-hydroxy-2-pyrone with methyl 2-chloroacrylate using cinchonine as an organocatalyst and (2) the <i>anti</i>-selective Cu-mediated S_N2′ reaction to afford the axially chiral vinylallene moiety

Enantioselective Total Synthesis of (+)-Iso-A82775C, a Proposed Biosynthetic Precursor of Chloropupukeananin

(+)-Iso-A82775C is a proposed biosynthetic precursor of the chloropupukeananin family and an important intermediate for related natural products. The first enantioselective total synthesis of (+)-iso-A82775C (18 steps, 2.2% overall yield) toward the eventual biomimetic total synthesis of chloropupukeananin is described. The key steps are (1) the enantioselective Diels–Alder reaction of 4-bromo-3-hydroxy-2-pyrone with methyl 2-chloroacrylate using cinchonine as an organocatalyst and (2) the <i>anti</i>-selective Cu-mediated S_N2′ reaction to afford the axially chiral vinylallene moiety

Hg(OTf)₂-Catalyzed Vinylogous Semi-Pinacol Rearrangement Leading to 1,4-Dihydroquinolines

An efficient method for the construction of dihydroquinoline derivatives possessing a quaternary carbon center is developed by an application of Hg(OTf)₂-catalyzed vinylogous semi-pinacol-type rearrangement. The reaction was found to be specifically catalyzed by mercury salt and to proceed via a bicyclic aminal

Hg(OTf)₂-Catalyzed Vinylogous Semi-Pinacol Rearrangement Leading to 1,4-Dihydroquinolines

An efficient method for the construction of dihydroquinoline derivatives possessing a quaternary carbon center is developed by an application of Hg(OTf)₂-catalyzed vinylogous semi-pinacol-type rearrangement. The reaction was found to be specifically catalyzed by mercury salt and to proceed via a bicyclic aminal

Asymmetric Total Synthesis of (−)-Maldoxin, a Common Biosynthetic Ancestor of the Chloropupukeananin Family

The total synthesis of pestheic acid based on an intramolecular S_NAr reaction without a nitro group and the asymmetric synthesis of (−)-maldoxin by a catalytic enantioselective oxidative dearomatization of pestheic acid are described. The reactivity of (−)-maldoxin as a diene in the Diels–Alder reaction is also investigated

Phagocytosis assay using IgG-coated PE beads.

<p>Representative histograms of PE fluorescence in differentiated HL-60 cells without (red) and with (blue) TAP-4PH treatment. HL-60 cells in the absence of IgG-coated PE beads are shown in the black-dotted line.</p

Chemical structure and fluorescence emission spectra of TAP-4PH.

<p>a) Chemical structure of the 1,3a,6a-Triazapentalene derivative TAP-4PH. b) Fluorescence emission spectra of TAP-4PH (10 μM) in aqueous and organic solvents. Green: acetonitrile; red: dichloromethane; blue: acetone; magenta: PBS.</p

Fluorescence imaging of live cells during neuronal differentiation of PC-12 cells.

<p>PC-12 cells were induced to differentiate into nerve cells by NGF. The cells at the indicated days after differentiation were treated with 50 μM TAP-4PH for 30 min. Top panels, TAP-4PH; bottom panels, bright-field images. Scale bar: 20 μm.</p

Time-dependent incorporation and distribution of TAP-4PH in A549 cells.

<p>a) Luminescence images of A549 cells incubated with 10 μM TAP-4PH for the indicated time periods. b) After incubation with 10 μM TAP-4PH for 30 min, the cells were washed and then incubated in fresh medium without TAP-4PH (time 0 min). Confocal luminescence images were taken after incubation for the indicated time periods. Scale bar: 20 μm.</p