A Practical Synthesis of 3-Acyl Cyclobutanones by [2 + 2] Annulation. Mechanism and Utility of the Zn(II)-Catalyzed Condensation of α-Chloroenamines with Electron-Deficient Alkenes
作者:Jeannette M. O’Brien、Jason S. Kingsbury
DOI:10.1021/jo102257k
日期:2011.3.18
New conditions for the conversion of simple tertiary amides to α-chloroenamines and their use in Zn(II)-catalyzed cycloadditionreactions with commercial α,β-unsaturatedcarbonylcompounds allows rapid, regiocontrolled access to 3-acyl cyclobutanones. Reactions take place at ambient temperature without solvent, giving strained [2 + 2] adducts with all-carbon-substituted quaternary carbon atoms. Ab
The reaction of bis(acetonitrile)bis(diethyl fumarate)cobalt(0) with dibromomethane gave diethyl trans-1,2-cyclopropanedicarboxylate in a 67% yield based on the cobalt complex. Dimethyl cis-1,2-cyclopropanedicarboxylate was obtained in a 52% yield from the reaction of dimethylmaleate with dibromomethane in the presence of acetonitrilebis(dimethylmaleate)nickel(0) accompanied by the formation of the
1, 5-Bis(trimethylsiloxy)-1, 5-dimethoxy-1, 4-pentadienes (7) can be prepared in good yield by silylation of the dianions of dimethyl glutarates (8). On treatment with titanium tetrachloride, 7 cyclise stereoselectively to dimethyl trans-cyclopropane-1, 2-dicarboxylates 10. Reaction of 7 with acetic anhydrode and titanium tetrachloride gives substituted cyclobutanes 22b–d.
Stereoselective Hydrolysis of Substituted Cyclopropanedicarboxylates with Pig Liver Esterase
作者:Paula Walser、Peter Renold、Victor N'Goka、Fatemeh Hosseinzadeh、Christoph Tamm
DOI:10.1002/hlca.19910740832
日期:1991.12.11
hydrolysis of the meso-cyclopropane-1,2-dicarboxylates 1a-3a, 4, 5a, 6a, and 9, containing various substituents at C(3), and of the rac-3-phenylcyclopropane-1,2-dicarboxylates7a, 8a, and 10 with pigliveresterase (PLE) is described. The stereoselectivtty and absolute configurations of the products were determined. An interpretation of results was attempted on the basis of a recent active-site model for
<b>Nuclear Magnetic Resonance Spectroscopy. Cyclopropane Derivatives</b>
作者:Dinshaw J. Patel、M. E. H. Howden、John D. Roberts
DOI:10.1021/ja00903a036
日期:1963.10
constants have been determined from the analysis of proton nuclear magnetic resonance spectra for a series of cyclopropane derivatives. The geminal and vicinal cyclopropyl couplings have opposite signs. Additional ^(13)C-H coupling constants have been obtained for cyclopropanes which support the conclusion that the hybridization of the carbon-hydrogen bonding orbitals in cyclopropanes is close to sp. The chemical