Base-promoted cycloaddition reactions of 1-aryl- or 1-aryl-7-substituted-4-oxahepta-1,6-diyne systems in DMSO have proven to involve an anionic intramolecularDiels-Alder process taking place even at room temperature in spite of the reaction suffering from temporary disruption of aromaticity. Although initially formed alpha-arylallenide anion can be protonated by DMSO, it can be back to the allenide
Gold(I)-Catalyzed Intermolecular Addition of Carbon Nucleophiles to 1,5- and 1,6-Enynes
作者:Catelijne H. M. Amijs、Verónica López-Carrillo、Mihai Raducan、Patricia Pérez-Galán、Catalina Ferrer、Antonio M. Echavarren
DOI:10.1021/jo8014769
日期:2008.10.3
Gold(I)-catalyzed addition of carbon nucleophiles to 1,6-enynes gives two different type of products by reaction at the cyclopropane or at the carbene carbons of the intermediate cyclopropyl gold carbenes. The 5-exo-dig cyclization is followed by most 1,6-enynes, although those bearing internal alkynes and alkenes react by the 6-endo-dig pathway. The cyclopropane versus carbene site-selectivity can
Kinetic Resolutions by Enantioselective Pauson-Khand-Type Reaction
作者:Dong Eun Kim、Jaesung Kwak、In Su Kim、Nakcheol Jeong
DOI:10.1002/adsc.200800657
日期:2009.1
A kineticresolution of 1-arylallyl propargyl ethers by enantioselectivePauson–Khand-typereaction catalysts was successfully carried out. While cationic rhodium(I) with a BINAP-based ligand having an electron-deficient phosphine is the choice for the slow reacting substrates, neutral iridium(I) with a BINAP-based ligand possessing an electron-rich phosphine provided excellent results for the more
Platinum-Catalyzed Cycloisomerization Reactions of Enynes
作者:Alois Fürstner、Frank Stelzer、Hauke Szillat
DOI:10.1021/ja0109343
日期:2001.12.1
PtCl(2) constitutes an efficient and practical catalyst for a set of different atom economical rearrangement reactions of enynes. This includes (i) a formal enyne metathesis reaction delivering 1,3-dienes, (ii) the formation of polycyclic vinylcyclopropane derivatives, and (iii) an unprecedented O-->C allyl shift reaction if unsaturated ethers are employed. Although these transformations produce significantly
A Novel platinum tetrachloride-catalyzed cyclorearrangement of allyl propynyl ethers to 3-oxabicyclo[4.1.0]heptenes.
作者:Jochanan Blum、Hanita Beer-Kraft、Yacoub Badrieh
DOI:10.1021/jo00122a043
日期:1995.9
Allyl propynyl ethers of general formula RC-CCH2OCH2CH=CHR' (1) undergo cyclorearrangement to 3-oxabicyclo[4.1.0]hept-4-enes (2) in oxygen-free benzene upon brief treatment at room temperature with catalytic amount of PtCl4. The transformation of 1 to 2 is assumed to involve platinum-allene intermediates. The structure of 7-(1-naphthyl)-6-phenyl-3-oxabicyclo[4.1.0]hept-4-ene (2c) has been determined by X-ray diffraction analysis. The-naphthyl and phenyl groups were shown to be oriented cis to each other. In the presence of [(CO2)Rh(mu-Cl)](2) the oxabicycloheptenes 2 undergo cyclopropane-ring cleavage. 6,7-Diphenyl-3-oxabicyclo[4.1.0lhept-4-ene (2b) forms the rhodocyclic complex 3b. In the absence of air, the oxygen-free analog of 1a, PhC=C(CH2)(3)CH=CH2 (4), rearranges to the unstable 7-phenylbicyclo[3.2.0]hept-1(7)-ene (5), which can be trapped by oxygen as stable 2-(2-oxo-2-phenylethyl)cyclopentanone (6).