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1.
Palladium[0]-mediated Ullmann cross-coupling of 1-bromo-2-nitrobenzene (1 R = H) and its derivatives with a range of beta-halo-enals, -enones, or -esters readily affords the corresponding beta-aryl derivatives, which are converted into the corresponding quinolines, 2-quinolones, phenanthridines, or 6(5H)-phenanthridinones on reaction with dihydrogen in the presence of Pd on C or with TiCl(3) in aqueous acetone. [reaction: see text] 相似文献
2.
Leiv K. Sydnes Karl F. S. Alnes Natalia Erdogan 《Monatshefte für Chemie / Chemical Monthly》2005,54(9):1737-1749
Several 2-alkyl-1,1,2-tribromocyclopropanes were treated with sodium hydroxide and ethanol under phase-transfer conditions.
Ring opening gave mixtures of the corresponding acetylenic diethyl ketals and acetals. When the steric bulk of the alkyl substituent
was increased acetal formation dominated, and in the case of 1,1,2-tribromo-2-(tert-butyl)cyclopropane, the acetal was formed as the only product. 相似文献
3.
The results of several approaches to make the 4,4,8-trimethyl-12-oxatricyclo[7.2.1.02,5]dodecane motif present in rumphellatins A–C are reported. The strategy adopted involved (9E)-12,12-dimethyl-5-oxatricyclo[8.2.0.04,6]dodec-9-en-11-ol as an intermediate, but when attempts were made to connect the third methyl group to the carbon skeleton by reacting the epoxide with MeLi under boron-trifluoride catalysis, an unprecedented transannular reaction occurred. The desired product was not formed; instead, compounds containing a tricyclo[6.3.0.02,5]undecane moiety were obtained, in one case in better than 70% yield. 相似文献
4.
Synthesis of (E)‐1,1‐Diethoxy‐3‐(3‐hydroxy‐3‐arylfuro[2,3‐b]quinoxalin‐2(3H)‐ylidene)propan‐2‐ones via Acid‐Catalyzed,Stereoselective 5‐Exo‐Dig Cyclization 下载免费PDF全文
Rustem Isanov Bjarte Holmelid Karl W. Törnroos Leiv K. Sydnes 《Journal of heterocyclic chemistry》2015,52(3):711-718
A number of 3‐(4,4,5,5‐tetraethoxy‐1‐hydroxy‐1‐arylpent‐2‐ynyl)quinoxalin‐2(1H)‐ones, obtained by reacting the lithium acetylide of 3,3,4,4‐tetraethoxybut‐1‐yne (TEB) with 3‐aroylquinoxalin‐2(1H)‐ones, appeared to undergo stereoselective cyclization in the 5‐exo‐Dig manner when heated at reflux in acidic, aqueous THF. In each case, the products were the corresponding (E)‐1,1‐diethoxy‐3‐(3‐hydroxy‐3‐arylfuro[2,3‐b]quinoxalin‐2(3H)‐ylidene)propan‐2‐ones and 1,1‐diethoxy‐3‐hydroxy‐3‐(3‐arylfuro[2,3‐b]quinoxalin‐2‐yl)propan‐2‐one, which were isolated in an approximate ratio of 2:1 in high total yield. Irrespective of the structure of the aryl group, both compounds were stable solids when kept in a refridgerator (3 °C), but when the latter product was dissolved in chloroform and stored at room temperature, it rearranged smoothly and quantitatively to the former compound within a few days. 相似文献
5.
The major products formed upon photolysis of ethyl 3-azido-4,6-difluorobenzoate in 2,2,2-trifluoroethanol-d3 has been elucidated by 1H NMR analysis of the product mixture. Among the products formed and structurally elucidated was a hitherto unreported product formed during photolysis of aryl azides, namely azoxybenzene 19. The structural assignments of the major components of the reaction mixture were aided by comparison with 1H NMR data from synthetic reference materials and compound isolation. MS, MS/MS, and HPLC analysis as well as UV spectroscopy was also employed in order to confirm and aid the structural analysis. 相似文献
6.
Ring opening of 1,1-dibromo-2-chloro-2-diethoxymethylcyclopropane in a mixture of ethanol and dichloromethane with 50% aqueous sodium hydroxide in the presence of triethylbenzylammonium chloride (TEBA) gave 3,3,4,4-tetraethoxybut-1-yne (TEB) in excellent yield. This alkyne appears to be thermally stable at least up to 150 °C. The compound is also stable in neutral and basic aqueous solutions. In acidic aqueous media, however, TEB is unstable and was converted to one or several products depending on the reaction conditions. The most useful reaction appears to be deketalization to give 1,1-diethoxybut-3-yn-2-one, which was obtained in quantitative yield under the optimum conditions. 相似文献
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8.
In the current work we present our preliminary evaluation of a new protein labeling strategy, namely oxidation labeling. We found that a bis(2-picolyl) amine analogue coordinating Cu+ was able to oxidize histidine to oxo-histedine in a small peptide by generating reactive oxygen species upon exposure to hydrogen peroxide. The bis(2-picolyl) amine unit was then incorporated into the natural product tautomycin via an oxime linker. The compound, which showed good activity toward protein phosphatase 1γ (PP1γ), will be used in oxidation labeling studies with PP1γ. 相似文献
9.
Treatment of a number of 2-substituted 1,1,2-tribromocyclopropanes with MeLi at −78°C gave the corresponding 1-bromocyclopropenes,
which were reacted with three cyclic dienes to yield the [4 + 2]-cycloadducts. Cycloaddition with 1,3-diphenylisobenzofuran
(DPIBF) gave the exo adducts, in most cases in excellent yield, whereas cyclopentadiene afforded endo adducts only, but in moderate yield. In most reactions with furan no adduct was formed, but two 1-bromocyclopropenes derivatives
with an aromatic side chain were exceptions and furnished mixtures of exo and endo adducts in moderate yields. 相似文献
10.
Summary. Treatment of a number of 2-substituted 1,1,2-tribromocyclopropanes with MeLi at −78°C gave the corresponding 1-bromocyclopropenes,
which were reacted with three cyclic dienes to yield the [4 + 2]-cycloadducts. Cycloaddition with 1,3-diphenylisobenzofuran
(DPIBF) gave the exo adducts, in most cases in excellent yield, whereas cyclopentadiene afforded endo adducts only, but in moderate yield. In most reactions with furan no adduct was formed, but two 1-bromocyclopropenes derivatives
with an aromatic side chain were exceptions and furnished mixtures of exo and endo adducts in moderate yields. 相似文献