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
variety of alkenes in the presence of a catalytic amount of Cr(CO)(5)(THF) at room temperature gives (2-furyl)cyclopropanes in good yields. These cyclopropanation reactions proceed via (2-furyl)carbene-chromium intermediates 4 formed in situ from ene-yne-ketones 3. Late transition metals, such as [RuCl(2)(CO)(3)](2), [RhCl(cod)](2), PdCl(2), and PtCl(2), also catalyze effectively the cyclopropanation of styrene
Stereodefined Substituted Cyclopropyl Zinc Reagents from Gem-Bismetallics
作者:Dov Beruben、Ilane Marek、Jean F. Normant、Nicole Platzer
DOI:10.1021/jo00113a032
日期:1995.4
1,1- or n,n-Bismetallic reagents bearing a methoxymethyl ether in the gamma position undergo cyclization at room temperature to give monometalated, diastereoselectively substituted cyclopropanes, The nature of the substituents is crucial for this diastereoselection, a pi-chelation between one metal and a properly located unsaturation, as well as 1,2-strain, are proposed to explain the steric outcome of these reactions.
Tandem Suzuki-Miyaura Coupling/Acid-Catalyzed Cyclization between Vinyl Ether Boronates and Vinyl Halides: A Concise Approach to Polysubstituted Furans
作者:Alexey N. Butkevich、Lieven Meerpoel、Ian Stansfield、Patrick Angibaud、Andrei Corbu、Janine Cossy
DOI:10.1021/ol4014574
日期:2013.8.2
Polysubstituted 2-(omega-hydroxyalkyl)furans were prepared by tandem Suzuki-Miyaura coupling/acid-catalyzed cyclization starting from appropriately substituted 3-haloallylic alcohols and dihydrofuran-, dihydropyran- or glycal-derived pinacol boronates.
A SIMPLE AND CONVENIENT METHOD FOR THE PREPARATION OF (Z)-b-IODOACROLEIN AND OF (Z)- OR (E)-Y-IODO ALLYLIC ALCOHOLS: (Z)- AND (E)-1-IODOHEPT-1-EN-3-OL