An efficient, direct nucleophilic allylicsubstitution of α-, β- and γ-substituted alcohols with enamines, using the Pd(OAc)2/PPh3 catalyst system and ZnBr2 as a promoter in CH2Cl2 at reflux, is reported. The reaction course was dependent on the steric hindrance at the α- or γ-positions with respect to the functionalized α-carbon, selectively affording in moderate to good yields, α- or γ-homoallyl
accessible tertiary propargyl vinyl ethers as substrates and imidazole as a catalyst to form up to two new rings, three new C−C bonds, six stereogenic centers and one transannular oxo‐bridge. The manifold is efficient, scalable and instrumentally simple to perform and entails a propargyl Claisen rearrangement–[1,3]H shift, an oxa‐6π‐electrocyclization, and an intramolecularDiels–Alderreaction.
Palladium-Catalyzed Alkene Carboalkoxylation Reactions of Phenols and Alcohols for the Synthesis of Carbocycles
作者:Derick R. White、Madeline I. Herman、John P. Wolfe
DOI:10.1021/acs.orglett.7b01975
日期:2017.8.18
triflate electrophile and exogenous alcohol or phenol nucleophiles are described. These transformations afford substituted indanyl or alkylidenecyclopentyl ethers in high yield with excellent diastereoselectivity. The transformations proceed through intermolecular capture of an intermediate [Pd(II)-alkene]+[OTf]− complex by the alcohol or phenol nucleophile.
Dual Palladium- and Proline-Catalyzed Allylic Alkylation of Enolizable Ketones and Aldehydes with Allylic Alcohols
作者:Ippei Usui、Stefan Schmidt、Bernhard Breit
DOI:10.1021/ol9001812
日期:2009.3.19
The dual Pd/proline-catalyzed α-allylation reaction of a variety of enolizable ketones and aldehydes with allylic alcohols is described. In this reaction, the choice of a large-bite angle ligand Xantphos and proline as the organocatalyst was essential for generation of the crucial π-allyl Pd intermediate from allylic alcohol, followed by nucleophilic attack of the enamine formed in situ from the corresponding
Versatile desilylative cross-coupling of silyl enol ethers and allylic silanes via oxovanadium-induced chemoselective one-electron oxidation
作者:Toshikazu Hirao、Takashi Fujii、Yoshiki Ohshiro
DOI:10.1016/s0040-4020(01)81753-1
日期:1994.8
The chemoselective cross-coupling of silylenolethers and allylic silanes to γ,δ-unsaturated ketones is achieved by the oxovanadium (V)-induced oxidative desilylation of the more readily oxidizable organosilicon compounds.