A stereoselective route to multi-substituted tetrahydropyrans by vinyl radical cyclization

The tin-mediated 6-exo-trig radical cyclization of the acetylenic β-alkoxy acrylates proceeded smoothly to give fully substituted tetrahydropyrans in good yields with high equatorial selectivity irrespective of the stereochemistry of the propargylic position.     

A facile synthetic route to a third-generation dendrimer with generation-specific functional aryl bromides

The synthesis of three third-generation dendrimers that selectively carry one aryl bromide functional group in the first, second, or third generation, respectively, is described. These functions, regardless of their location, can be chemically modified by Suzuki cross-coupling chemistry with p-tert-butylbenzene boronic ester.     

A facile asymmetric route to (-)-aphanorphine

8O-methylaphanorphine was synthesized from 4-methoxyphenylacetaldehyde in 36% overall yield and in nine steps, featuring the formation of ring B via a Friedel-Crafts alkylative cyclization with the concomitant stereospecific introduction of the benzylic quaternary carbon center. The current work constitutes an efficient enantioselective formal synthesis of 3-benzazepine marine alkaloid (-)-aphanorphine.     

A facile route to 5-alkyl-2(3H)-furanones by photoisomerisation of enedicarbonyl compounds

A new and useful synthesis of a title compounds is reported. They can be obtained easily by photocyclization of enedicarbonyl compounds 3 and 4. A different behaviour, ascribed to the geometry of a double bond, is observed; 3 are converted only to butenolides 5, while trans-isomers 4 are converted into alkyl-furyl-ketones 5 and 6. A possible mechanism is described.     

A route to conformationally restricted antioestrogens by coupling of a vinyl triflate with an aryl zinc chloride

Palladium complex catalysed coupling of a benzocycloheptenyl triflate with aryl zinc chlorides gives an efficient approach to the synthesis of conformationally restricted antioestrogens.     

A facile synthetic route to (η-benzoyleyclopentadienyl) metal compounds

A reaction between cyclopentadienylsodium and ethyl benzoate in refluxing THF produces (benzoylcyclopentadienyl)sodium (4) in 70–80% yield. Subsequent treatment of 4 in ethanol solution with thallium ethoxide affords (benzoyleyclopentadienyl)thallium (3) in nearly quantitative yield. Reactions of 3 with Mn(CO)₅Br, Re(CO)₅Br, [Rh(CO)₂Cl]₂ or FeCl₂ lead to the respective η⁵-benzoylcyclopentadienyl derivatives of these metals, and demonstrate the utility of 3 in organometallic syntheses. Reactions of several of these organometallic ketones with cymantrenyllithium [(η⁵-C₅H₄Li)Mn(CO)₃] provide a useful new route to bimetallic compounds.     

A facile route to cyclopentenones by friedel-crafts acylation

Various cyclopentenones are obtained in fair to high yields when ethylenic acyl bromides are condensed with cyclohexene at low temperature. With less reactive reagents, condensation occurs at 0 °C, leading to β-chloro-ketones. A muscone precursor is obtained in two steps with excellent yields.     

Palladium(0)-promoted cross-coupling of allenylmetal compounds with aryl and vinyl iodides. A novel route to aryl- and vinyl-substituted allenes

The reaction of allenylmetal compounds, RR{′}CCCHM (I), with aryl and vinyl iodides, R I, have been studied. With Pd(PPh₃)₄ as catalyst a highly regioselective formation of allenes, RR{′}CC CHR″ (II), has been observed for MgCl, Cu, Cu_1/2,Li_1/2, Ag, Ag_1/2Li_1/2, or ZnCl, but not Li. The reaction of the iodides proceeds with retention of configuration.     

Palladium-catalyzed borylation of aryl halides or triflates with dialkoxyborane: A novel and facile synthetic route to arylboronates

A direct borylation of aryl halides or triflates with dialkoxyborane was investigated. The coupling reaction of pinacolborane with aryl halides or triflates in the presence of a catalytic amount of PdCl(2)(dppf) together with a base provided arylboronates in high yields. The product distributions were strongly dependent on the base employed, and the tertiary amine, especially Et(3)N, was effective for the selective formation of the boron-carbon bond. The reaction conditions were so mild that arylboronates having a variety of functional groups such as carbonyl, cyano, and nitro groups were readily prepared.     

A novel, facile route to beta-fluoroamines by hydrofluorination using superacid HF-SbF(5)

A range of unsaturated amines and sulfonamides were converted to beta-fluoro nitrogen analogues after hydrofluorination in superacid HF-SbF(5), based on the formation of highly reactive electrophilic intermediates.     

Preparation of arylphosphonates by the reaction of aryl halides with tris(trimethylsilyl) phosphite under homogeneous catalysis conditions

The reaction of tris(trimethylsilyl) phosphite with aryl bromides under homogeneous catalysis conditions gives bis(trimethylsilyl)arylphosphonates. The desilylation of these phosphonate products with methanol leads to arylphosphonic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1461–1462, June, 1991.     

Het(aryl)isatin to het(aryl)aminoindoline scaffold hopping: A route to selective inhibitors of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are a large family of zinc-dependent endoproteases known to exert multiple regulatory roles in tumor progression. A variety of chemical classes have been explored for targeting individual MMP isoforms. In the present study, we further developed our isatin based scaffold BB0223107 capable of binding to and inactivating MMP-2 in a zinc-independent manner (Agamennone et al., 2016). Forty four new compounds were synthesized based on the modified BB0223107. All compounds were tested in enzyme inhibition assays against MMP-2, ?8 and ?13. SAR studies demonstrated that 5-het(aryl)-3-aminoindolin-2-ones (37–39) were active toward MMP-2 and MMP-13. The most potent compounds 33 and 37 displayed an IC₅₀ of 3 µM against MMP-13 and showed a negligible activity toward MMP-8; almost all new compounds were inactive toward MMP-8. Replacement of the isatin ring with a biaryl system (compound 33) did not decrease the potency against MMP-13 but reduced the selectivity. Structure-based computational studies were carried out to rationalize the inhibitory activity data. The analysis of binding geometries confirmed that all fragments occupied the S1′ site in the three enzymes while no ligand was able to bind the catalytic zinc ion. To the best of our knowledge, this is the first example of 3-aminoindolin-2-one-based MMP inhibitors that, based on the computer modeling study, do not coordinate the zinc ion. Thus, the het(aryl)-3-aminoindolin-2-one derivatives emerge as a drug-like and promising chemotype that, along with the hetaryl variations, represents an alternative and thrifty tool for chemical space exploration aimed at MMP inhibitor design.     

手性位移试剂Eu(dcm)~3的一个改进合成方法

我们对H(dcm)的Whitesides合成路线的关键步骤龙脑酰甲烷的合成和缩合反应进行了重要的改进。     

A facile tandem radical cyclization route to propellanes and its application to a total synthesis of modhephene

A facile and versatile tandem radical cyclization route to propellanes from dieneyne compounds was developed and was applied to the total synthesis of modhephene.     

A facile route to 4,5,6,7-tetrahydrothiophenes and benzothiophenes

2-Substituted tetrahydro- and cyclopentathiophenes 2 were produced in high yields by treatment of the semi-cyclic trisubstituted 1,4-diketones 1 such as 2-phenacylcyclohexan-1-one, 2-acetonylcyclohexan-1-one, and 2-phenacylcyclopentan-1-one, with Lawesson's reagent.     

A facile route to the fabrication of morphology-controlled Sb2O3 nanostructures

We report in this paper a facile hydrothermal route for the preparation of Sb₂O₃ nanoribbons assembly with different aspect ratio and Sb₂O₃ polyhedral nanoparticles. Study indicates that the ratio of water and ethanol affects the morphology, size and crystal phase of Sb₂O₃ assembly building blocks. In a mixed alcohol and water solution, the orthorhombic Sb₂O₃ nanoribbons with a length of ～4 μm and a width of 400 nm were assembled into rod-like structures, while a length of ～3 μm and a width of 300 nm Sb₂O₃ nanoribbons were assembled into quadrangle structures with the increase of the water ratio. In the absolute alcohol solution, the cubic Sb₂O₃ particles with polyhedral morphology were formed. PL spectra indicate that the morphology strongly affects the luminescence property. The possible formation mechanisms involving the surfactant-assisted self-assembly and the confined growth were also proposed for the formation of the bundled nanoribbons and polyhedral granules, respectively.     

A facile synthesis of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl)acetamidines

<正>A series of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl) acetamidines was synthesized by reacting ethyl(1H)-N-(4-oxo-2-phenylquinazolin-3(4H)-y1)ethanimidoate(2) and suitable reactive aromatic amines.Structures' determination of the synthesized compounds was carried out using spectroscopic techniques including IR,~1H NMR,and mass spectrometry. Structural effects on reactivity were also studied.     

Negishi coupling between alpha-alkyl(aryl)thio vinyl zinc chloride and alpha-bromo vinyl ether: a convergent synthesis of 2-alkoxy-3-alkyl(aryl)thiobuta-1,3-dienes

[reaction: see text] A convergent approach for the stereoselective synthesis of 2-alkoxy-3-alkyl(aryl)thiobuta-1,3-dienes has been developed. It was found that Negishi coupling between alpha-alkyl(aryl)thio vinyl zinc chloride and alpha-bromo vinyl ether or Negishi coupling between alpha-bromo vinyl sulfide and alpha-alkoxy vinyl zinc chloride provided the best yield and stereoselectivity.     

A facile and general route to 4-substituted-2 butenolides

Grignard reagents react with 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride and produce in high yields the corresponding substituted bicyclo-γ-butanolides. These lactones produce the title compounds by retro Diels-Alder reaction during distillation.