Regio- and stereoselectivity in the cyclization of enolates derived from 4,5-, 5,6-, and 6,7-epoxy-1-phenyl-1-alkanones. Competition between C- and O-alkylation
作者:Paolo Crotti、Valeria Di Bussolo、Lucilla Favero、Franco Macchia、Mauro Pineschi、Elio Napolitano
DOI:10.1016/s0040-4020(99)00226-4
日期:1999.4
The results obtained in the base-catalyzed intramolecular cyclization of enolates derivedfrom some representative 4,5-, 5,6-, and 6,7-epoxy ketones and of the corresponding alkenes are discussed. The LHMDS/Sc(OTf)3 protocol on epoxy ketones appears to be a valuable tool for the stereoselective obtainment of the corresponding cyclic γ-hydroxy ketones (γ-HKs).
A Telluride-Triggered Nucleophilic Ring Opening of Monoactivated Cyclopropanes<sup>1</sup>
作者:Dmitry V. Avilov、Mahesh G. Malusare、Engin Arslancan、Donald C. Dittmer
DOI:10.1021/ol0492804
日期:2004.6.1
[reaction: see text] Acylcyclopropanemethanol tosylates undergo rapid ringopening at room temperature by the action of lithium telluride to produce the enolate of a homoallylic ketone. The enolate can be protonated to yield the corresponding ketone or treated with benzaldehyde to give the aldol product with good syn or anti diastereoselectivity depending on the conditions.
stereoselective routes towards isopropenylcyclopropanes have been devised. Secondary cis-isopropenylcyclopropylcarbinols have been obtained either by regio- and stereoselective hydroxy-directed cyclopropanation of the corresponding dienols or from bicyclic cyclopropyl lactones derived from intramolecularcyclopropanation of allylicdiazoacetates. Contrary to previous reports, base-induced 1,3-elimination of γ-epoxy
Acidic isomerization of vicinally substituted (cis)-acceptor-donor cyclopropanes via an open ring mechanism
作者:Luc Dechoux、Eric Doris
DOI:10.1016/s0040-4039(00)73037-1
日期:1994.3
Many (cis)-cyclopropanes bearing 1-electronwithdrawing and 2-hydroxymethylene groups were synthetised and isomerized under midl acidic conditions to afford the corresponding trans isomers. The mechanism is reported.
Diastereocontrol in the opening of vic-acceptor-donor cyclopropanes. Application to the synthesis of (cis) 1-EWG-2-hydroxymethylcyclopropanes
作者:Luc Dechoux、Eric Doris、Louis Jung、Jean François Stambach
DOI:10.1016/s0040-4039(00)77266-2
日期:1994.8
Basic intramolecular ring opening reactions of vicinally substituted acceptor-donnor (trans)-cyclopropanes were studied. An application to the diastereoselective synthesis of (cis)-1-EWG-2-hydroxymethylcyclopropanes is presented.