Diastereoselective allylzincation of γ-oxygenated vinyllithiums bearing functionalized side-chains
摘要:
Allylzincation of gamma-oxygenated vinyllithiums bearing functionalized side-chains proved to be more difficult than that reported in the case of gamma-oxygenated vinyllithiums with unfunctionalized side-chains. However, when allylzincation occurs it gives the corresponding linear compounds with high diastereoselection as a consequence of the zinc being coordinated by the two oxygen atoms of the methoxymethyl ether moiety. (C) 2004 Elsevier Ltd. All rights reserved.
Stereodefined Substituted Cyclopropyl Zinc Reagents from Gem-Bismetallics
摘要:
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.