The direct preparation of functionalised cyclopropanes from allylic alcohols or α-hydroxyketones using tandem oxidation processes
作者:Graeme D. McAllister、Magalie F. Oswald、Richard J. Paxton、Steven A. Raw、Richard J.K. Taylor
DOI:10.1016/j.tet.2005.12.078
日期:2006.7
carried out in the presence of a stabilised sulfurane, and the intermediate α,β-unsaturated carbonyl compound undergoes in situ cyclopropanation. By using a combination of stabilisedphosphorane and sulfurane, the direct conversion of allylic alcohols or α-hydroxyketones into functionalised cyclopropanes is achieved, with in situ cyclopropanation being followed by Wittig olefination, or vice versa. The
The 1,t-2,t and 1,t-2,c-isomers of 1,2-dibenzoyl-3-phenylcyclopropanes have been prepared by the cycloaddition of carbonyl-stabilized sulfur ylides to trans-chalcones under phase-transfer conditions. The configurations of the isomers were characterized by IR- and 1H-NMR-spectral studies.
Indium(I) bromide-promoted stereoselective preparation of cyclopropanes via sequential aldol-type coupling/elimination/Michael-induced ring closure reaction from α,α-dichloroacetophenone and aldehydes
作者:Clovis Peppe、Rafael Pavão das Chagas、Robert Alan Burrow
DOI:10.1016/j.jorganchem.2008.08.011
日期:2008.10
an-1-ones which can be converted to their trans-prop-2-en-1-ones derivatives upon reaction with an extra equivalent of InBr. The enones undergo Michael-induced ringclosurereactions with an extra equivalent of the initial enolate to afford the corresponding cyclopropane derivatives, according to a sequenced reaction mechanism.
The Formation of Cyclopropane Derivatives Bearing 1,2-Dicarbonyl Groups through Tandem Michael-Favorskii-Type Reactions with(E)-?-Styrylselenonium Triflate
A novel tandemMichael–Favorskii-typereaction is described. Treatment of active methylene carbanions, prepared by the reaction of NaH and active methylene compounds, with (E)-β-styrylselenonium triflate in DMF at 70 °C for 3 h gave cyclopropanederivativesbearing1,2-dicarbonylgroups in moderate to good yields. On the other hand, the carbanions derived from malonates reacted with the selenonium