Catalytic Allylic C−H Acetoxylation and Benzoyloxylation via Suggested (η<sup>3</sup>-Allyl)palladium(IV) Intermediates
作者:Lukasz T. Pilarski、Nicklas Selander、Dietrich Böse、Kálmán J. Szabó
DOI:10.1021/ol9023369
日期:2009.12.3
Palladium-catalyzed allylic acetoxylations and benzoyloxylations were carried out using iodonium salts. The reactions proceed under mild conditions with high regio- and stereoselectivity. The catalysis can be performed under both acidic and nonacidic conditions without use of BQ or other external oxidants and activator ligands. Deuterium labeling experiments clearly show that the catalytic reaction
High 1,2-Asymmetric Induction in Radical Reactions: Radical Addition to<i>γ</i>-Hydroxy<i>α</i>,<i>β</i>-Unsaturated Carboxylic Esters and Sulfones
作者:Katsuyuki Ogura、Akio Kayano、Motohiro Akazome
DOI:10.1246/bcsj.70.3091
日期:1997.12
High 1,2-asymmetric induction was realized by the addition of a 1-hydroxy-1-methylethyl radical to conformationally flexible (E)-γ-hydroxy α,β-unsaturated carboxylic esters and sulfones (1 and 2, respectively). Upon the irradiation (> 290 nm) of (E)-1 and benzophenone in 2-propanol, the 1-hydroxy-1-methylethyl radical was generated in situ and added to (E)-1 with high anti-stereoselectivity. The bulkier
A novel synthetic method for γ-acetoxy-(E)-α,β-unsaturated esters by the palladium catalyzed regio- and stereoselective acetoxylation of β,γ-unsaturated esters
A new syntheticmethod for γ-acetoxy-α,β-unsaturatedesters by the acetoxylation of β,γ-unsaturatedesterscatalyzed by PdCl2 in the presence of KOAc and pentyl nitrite in acetic acid is presented. The reaction takes place at γ-position of the esters regioselectively with double bond migration to α,β-position. The E configuration of the double bond was confirmed by NMR analysis. Preliminary investigation
Nucleophilic Displacement Reactions of 4-(Nosyloxy)-2,3- unsaturated Esters and 2-(Nosyloxy)-3,4-unsaturated Esters
作者:Robert V. Hoffman、Bryon S. Severns
DOI:10.1021/jo960477m
日期:1996.1.1
It has been found that 4-(nosyloxy)-2,3-unsaturated esters 2 undergo direct displacement with a wide variety of nucleophiles and yield 4-substituted-2,3-unsaturated products cleanly and in generally good yields. These materials thus have very good synthetic potential for the formation of densely functionalized unsaturated esters. 2-(Nosyloxy)-3,4-unsaturated esters as exemplified by methyl 2-(nosyloxy)-3-butenoate (3d) also undergo direct displacement with a range of good nucleophiles; however, the resulting substitution products are prone to rearrangements and tautomerism, as is the starting material itself, so that the synthetic utility of these compounds is limited.