Counteranion-controlled regioselectivity in palladium-catalyzed allylic amination of dienyl allylic carbonates
作者:Meng-Lan Shen、Pu-Sheng Wang、Liu-Zhu Gong
DOI:10.1016/j.tet.2021.131996
日期:2021.3
A regioselective Pd-catalyzed allylic amination reaction of dienyl allylic carbonates and aromatic amines has been developed by means of phosphoramidte-palladium catalysis. The regioselectivity could be altered by the counterion of the π-allylpalladium intermediate. As a result, either branched Z-dienyl allylic amines or linear conjugated allylic amines were generated in high levels of regioselectivity
The regioselectivity of the fluorination of various allylic and β-dienoic alcohols with DAST has been studied. Substituent effects are important in these reactions; a strong preference for the secondary fluorides versus the primary ones is observed, especially in the case of alkyl and aryl substituted derivatives.
Chemoselective Rh-Catalyzed Allylic Alkylations of Chelated Enolates using Dienylcarbonates
作者:Saskia Hähn、Uli Kazmaier
DOI:10.1002/ejoc.201100350
日期:2011.7.14
catalyst not only for highly regio- but also chemoselectiveallylicalkylations of chelated enolates. In contrast to Pd-catalyzed reactions, the Rh-catalyzed version shows also a high degree of regioretention and proceeds without isomerization. Allylic substrates with competitive allylic subunits react selectively at the sterically least hindered allylic position, in comparison to Ru-catalyzed processes
A novel DABCO-catalyzed Ireland-Claisen [3,3]-rearrangement of allylic acrylates to give a-methylene-γ,δ -unsaturated carboxylic acids in the presence of an excess of TMSCl and DBU in refluxing acetonitrile was developed. The protocol provides an easy entry to a-methylene-γ,δ-unsaturated carboxylic acids from allylic alcohols in good yields.
3-Triethylsilyloxypentadienyllithium, a Versatile 1,3-Diene- or Vinyl Ketone-Building Block
作者:Wolfgang Oppolzer、Roger L. Snowden、Dana P. Simmons
DOI:10.1002/hlca.19810640705
日期:1981.11.4
(Table 1) aldehydes and ketones attack preferentially the γ-position of 4(Table 2). The desired γ-products 6 may be directly subjected to inter- and intramolecular [4 + 2]-additions as demonstrated by the reactions 5a ( 6d) 7 and 6h 19(Schemes 4 and 12). Alternatively, smooth fluoride-promoted silylether-cleavage 6 11(Scheme 8) provides a convenient approach to substituted vinyl ketones such as to