Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: KEGG:D02259 (
NaI
)
1,823
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
An alpha-carbonyl radical cyclization approach toward synthesis of angular triquinanes is described. As a model study, conjugate addition of 4-(trimethylsilyl)-3-butynylmagnesium chloride to enone 7 followed by trapping of the enolate with chlorotrimethylsilane gave trimethysilyl enol ether 8. Iodination of 8 with a mixture of
NaI
and m-CPBA afforded iodo ketone 6. Radical cyclization of 6 effected by Bu(3)SnH and AIBN gave 5. Epoxidation of 5 with m-CPBA yielded epoxy ketone 9. Desilylation and rearrangement of 9 by
formic acid
gave aldehyde 4. Aldol condensation and dehydration furnished angular triquinane skeleton 3. Total synthesis of (-)-5-oxosilphiperfol-6-ene (1) was accomplished in 12 steps starting from keto ester 14 based on this route. Conjugate addition of 3-hexynylmagnesium bromide to chiral ester 13 followed by treatment with chlorotrimethylsilane gave intermediate 15. Iodination of 15 with a mixture of
NaI
and m-CPBA gave alpha-iodo ester 12. Intramolecular radical cyclization of 12 gave ester 11. Reduction of 11 by LiAlH(4) yielded alcohol 16. On treatment with m-CPBA, alcohol 16 was converted to the corresponding epoxide 17, which was subjected to the epoxy-ketone rearrangement using BF(3) etherate as a catalyst to give ethyl ketone 18. Subsequent oxidation of 18 with PCC afforded aldehyde 10. Intramolecular aldol condensation of 10 yielded tricyclic compound 19. Methylation of 19 gave 20. Conjugate addition of lithium dimethylcuprate to 20 followed by trapping of the resulting enolate with chlorotrimethylsilane gave 21. Oxidation of 21 by DDQ afforded enantiomerically pure (-)-5-oxosilphiperfol-6-ene (1). Racemic (+/-)-1was also synthesized in the same manner in order to determine the optical purity of chiral product (-)-1. The gas chromatographic analysis with a chiral column proved that 1 has high enantiomeric purity. A single-crystal X-ray analysis of 2,4-dinitrophenylhydrazone 22 was performed to unambiguously confirm the stereochemistry of 19.
...
PMID:alpha-Carbonyl Radical Cyclization Approach toward Angular Triquinanes: Total Synthesis of Enantiomerically Pure (-)-5-Oxosilphiperfol-6-ene. 1167 39
Pt-Pd bimetallic alloy nanostructures with highly selective morphologies such as cube, bar, flower, concave cube, and dendrite have been achieved through a facile one-pot solvothermal synthesis. The effects of shape-controllers (sodium dodecyl sulfate (SDS), ethylenediamine-tetraacetic acid disodium salt (EDTA-2Na),
NaI
) and solvents (water/DMF) on the morphologies were systematically investigated. The electrocatalytic activities of these Pt-Pd alloy nanostructures toward
formic acid
oxidation were tested. The results indicated that these alloy nanocrystals exhibited enhanced and shape-dependent electrocatalytic activity toward
formic acid
oxidation compared to commercial Pt black and Pt/C catalysts.
...
PMID:Solvothermal synthesis of Pt-Pd alloys with selective shapes and their enhanced electrocatalytic activities. 2240 65
This article reports the design and successful implementation of a one-pot, polyol method for the synthesis of penta-twinned Pd nanowires with diameters below 8 nm and aspect ratios up to 100. The key to the success of this protocol is the controlled reduction of Na
2
PdCl
4
by diethylene glycol and ascorbic acid through the introduction of
NaI
and HCl. The I
-
and H
+
ions can slow the reduction kinetics by forming PdI
4
2-
and inhibiting the dissociation of ascorbic acid, respectively. When the initial reduction rate is tuned into the proper regime, Pd decahedral seeds with a penta-twinned structure appear during nucleation. In the presence of I
-
ions as a selective capping agent toward the Pd(100) surface, the decahedral seeds can be directed to grow axially into penta-twinned nanorods and then nanowires. The Pd nanowires are found to evolve into multiply twinned particles if the reaction time is extended beyond 1.5 h, owing to the involvement of oxidative etching. When supported on carbon, the Pd nanowires show greatly enhanced specific electrocatalytic activities, more than five times the value for commercial Pd/C toward
formic acid
oxidation and three times the value for Pt/C toward oxygen reduction under an alkaline condition. In addition, the carbon-supported Pd nanowires exhibit greatly enhanced electrocatalytic durability toward both reactions. Furthermore, we demonstrate that the Pd nanowires can serve as sacrificial templates for the conformal deposition of Pt atoms to generate Pd@Pt core-sheath nanowires and then Pd-Pt nanotubes with a well-defined surface structure.
...
PMID:One-Pot Synthesis of Penta-twinned Palladium Nanowires and Their Enhanced Electrocatalytic Properties. 2882 63
