Facile and Selective Cleavageof Allyl Ethers Based on Palladium(0)-Catalyzed Allylic Alkylationof<i>N</i>,<i>N</i>′-DimethylbarbituricAcid
作者:Hirokazu Tsukamoto、Yoshinori Kondo
DOI:10.1055/s-2003-39320
日期:——
The classical palladium(0)-catalyzed allylic alkylation of N,N'-dimethylbarbituric acid can be applied to the facile and selective cleavage of allylic alkyl ethers to release the corresponding alcohols in excellent yield.This reaction proceeds under neutral conditions without any additive to activate the allyl ethers and tolerates various functional groups, such as ester, ether, ketone, alkyl and aryl
Remarkable Solvent Effect on Pd(0)-Catalyzed Deprotection of Allyl Ethers Using Barbituric Acid Derivatives: Application to Selective and Successive Removal of Allyl, Methallyl, and Prenyl Ethers
Pd(0)-catalyzed deprotection of allylethers using barbituric acid derivatives in protic polar solvent such as MeOH and aqueous 1,4-dioxane proceeds at room temperature without affecting a wide variety of functional groups. Control of the reaction temperature allows selective and successive cleavage of allyl, methallyl, and prenyl ethers. A study of ligand effects on the deprotection reveals that the
Child's play! Allyl ethers as protecting groups for hydroxyl functions can be removed readily with a combination of DIBAL and catalytic amounts of [NiCl2 (dppp)]. Propene is expelled in this remarkably selective reaction, and a nickel-catalyzed hydroalumination-elimination pathway is proposed [Eq. (a)]. dppp=propane-1,3-diylbis(diphenylphosphane).
Chromatography-free Pd-catalyzed deprotection of allyl ethers using PS-DEAM as a scavenger of boronic acids and Pd catalyst
Pd(PPh3)4-catalyzed cleavage of allylic alkyl ethers using phenylboronic acid can effectively release Pd-free parent alcohols. Furthermore, chromatography-free deallylation can be conducted by using vinylboronic anhydride pyridine complex as an allyl scavenger with a catalytic amount of Pd(OAc)2 and 4-(diphenylphosphino)benzoic acid instead of Pd(PPh3)4 to yield the desired products in high purities and
Oxidation of acyclic alkenes and allyl and benzyl ethers with DIB/t-BuOOH/Mg(OAc)2
作者:Thanapat Sastraruji、Stephen G. Pyne、Alison T. Ung
DOI:10.1016/j.tet.2011.10.112
日期:2012.1
Oxidation of (11Z)-1′,2′-didehydrostemofoline with DIB/TBHP/Mg(OAc)2·4H2O resulted in oxidative cleavage of the C-11–C-12 double bond instead of the desired allylic oxidation of the 1-butenyl side chain. Stemofoline gave a similar result. The oxidation of more simple terminal alkenes was regioselective and gave vinyl ketones while allyl and benzyl ethers gave acrylate and benzoate esters, respectively