We advance the chemistry of apical chlorine substitution in the 2D superatomic semiconductor Re6Se8Cl2 to build functional and atomically precise monolayers on the surface of the 2D superatomic ...Re6Se8 substrate. We create a functional monolayer by installing surface (2,2′-bipyridine)-4-sulfide (Sbpy) groups that chelate to catalytically active metal complexes. Through this reaction chemistry, we can create monolayers where we can control the distribution of catalytic sites. As a demonstration, we create highly active electrocatalysts for the oxygen evolution reaction using monolayers of cobalt(acetylacetonate)2bipyridine. We can further produce a series of catalysts by incorporating organic spacers in the functional monolayers. The structure and flexibility of the surface linkers can affect the catalytic performance, possibly by tuning the coupling between the functional monolayer and the superatomic substrate. These studies establish that the Re6Se8 sheet behaves as a chemical pegboard: a surface amenable to geometrically and chemically well-defined modification to yield functional monolayers, in this case catalytically active, that are atomically precise. This is an effective method to generate diverse families of functional nanomaterials.
Correction to “Total Synthesis of (−)-Sarain A” Becker, Michael H; Chua, Peter; Downham, Robert ...
Journal of the American Chemical Society,
04/2018, Letnik:
140, Številka:
15
Journal Article
Total Synthesis of (−)-Sarain A Becker, Michael H; Chua, Peter; Downham, Robert ...
Journal of the American Chemical Society,
10/2007, Letnik:
129, Številka:
39
Journal Article
Recenzirano
This article describes the details of our synthetic studies toward the complex marine alkaloid sarain A. Various strategies were conceived, setbacks encountered, and solutions developed, ultimately ...leading to a successful enantioselective total synthesis. Our route to (−)-sarain A features a number of key steps, including an asymmetric Michael addition to install the C4‘−C3‘−C7‘ stereotriad, an enoxysilane-N-sulfonyliminium ion cyclization to set the C3 quaternary carbon stereocenter, and assemble the diazatricycloundecane core, a ring-closing metathesis to construct the 13-membered ring, an intramolecular Stille coupling to fashion the unsaturated 14-membered macrocycle, and a late-stage installation of the tertiary amine−aldehyde proximity interaction.
The total synthesis of (±)-gelsemine (1) is described. A defining phase of the effort involved recourse to a strategic oxetane ring (see compound 25). It was constructed anticipating an ...intramolecular displacement of the carbon (C17)−oxygen (O4) bond (see product 48). A key intermediate in the stereospecific elaboration of the oxetane linkage was enone 22, which was susceptible to two β-face attacks leading to 24 and, thence, 25. Three sigmatropic rearrangements were employed in building the bridgehead (C20) and the spiroanilide (C7) quaternary centers en route to gelsemine.
We describe the pharmacological and pharmacokinetic profiles of SCH 486757, a nociceptin/orphanin FQ peptide (NOP) receptor agonist that has recently entered human clinical trials for cough. SCH ...486757 selectively binds human NOP receptor (
K
i
=
4.6
±
0.61
nM) over classical opioid receptors. In a guinea pig capsaicin cough model, SCH 486757 (0.01–1
mg/kg) suppressed cough at 2, 4, and 6
h post oral administration with a maximum efficacy occurring at 4
h equivalent to codeine, hydrocodone, dextromethorphan and baclofen. The antitussive effects of SCH 486757 (3.0
mg/kg, p.o.) was blocked by the NOP receptor antagonist J113397 (12
mg/kg, i.p.) but not by naltrexone (10
mg/kg, p.o.). SCH 486757 does not produce tolerance to its antitussive activity after a 5-day BID dosing regimen. After acute and chronic dosing paradigms, SCH 486757 (1
mg/kg) inhibited capsaicin-evoked coughing by 46
±
9% and 40
±
11%, respectively. In a feline mechanically-evoked cough model, SCH 486757 produces a maximum inhibition of cough and expiratory abdominal electromyogram amplitude of 59 and 61%, respectively. SCH 486757 did not significantly affect inspiratory electromyogram amplitude. We examined the abuse potential of SCH 486757 (10
mg/kg, p.o.) in a rat conditioned place preference procedure which is sensitive to classical drugs of abuse, such as amphetamine and morphine. SCH 486757 was without effect in this model. Finally, SCH 486757 displays a good oral pharmacokinetic profile in the guinea pig, rat and dog. We conclude that SCH 486757 has a favorable antitussive profile in preclinical animal models.
The synthesis of (±)-gelsemine Lin, Hong; Ng, Fay W; Danishefsky, Samuel J
Tetrahedron letters,
01/2002, Letnik:
43, Številka:
4
Journal Article
Recenzirano
The synthesis of (±)-gelsemine has been completed from tetracyclic intermediate
2
via a stereospecific 3,3-rearrangement followed by a one carbon excision to convert a δ-lactam (
13
) to a γ-lactam (
...19
).
Graphic
The synthesis of key intermediate
30
en route to gelsemine has been accomplished from known aldehyde
10
via oxetane
19
featuring stereospecific Claisen rearrangement and Lewis acid-catalyzed oxetane ...ring opening.
Graphic
We report two new helicenes derived from the double fusion of an acene with two perylene diimide (PDI) subunits. These PDI‐helicene homologs exhibit very different structural and electronic ...properties, despite differing by only a single ring in the link between the PDI units. The shorter inter‐PDI link brings the two PDI subunits closer together, and this results in the collision of their respective π‐electron clouds. This collision facilitates intramolecular through‐space electronic delocalization when the PDI‐helicene is reduced.
Two helicenes were synthesized by double fusion of an acene with two perylene diimide (PDI) subunits. These PDI‐helicene homologs show different structural and electronic properties, despite differing by only a single ring in the link between the PDI units. The shorter link brings the two PDI subunits closer together, and this results in the collision of their respective π‐electron clouds.
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