Tandem Pd(II)-Catalyzed Vinyl Ether Exchange−Claisen Rearrangement as a Facile Approach to γ,δ-Unsaturated Aldehydes
作者:Xudong Wei、Jon C. Lorenz、Suresh Kapadia、Anjan Saha、Nizar Haddad、Carl A. Busacca、Chris H. Senanayake
DOI:10.1021/jo062548f
日期:2007.5.1
A sequential allyl vinyl ether formation−Claisen rearrangement process catalyzed by a palladium(II)−phenanthroline complex is reported. The effects of allylic alcohol structure, type of vinylating agent, and palladium catalysts are discussed. This method provides a convenient approach to γ,δ-unsaturated aldehydes under mild conditions that avoid the use of toxic Hg(II) catalysts. The new methodology
A photocatalytic synthesis of homoallyl ketones was achieved via a one-pot procedure starting from a Norrish Type I reaction of cyclopentanones, followed by a decatungstate-catalyzed hydroacylation of electron-deficient olefins by the resulting 4-pentenals. The site-selective formyl H-abstraction in the second step can be explained by radical polar effects in the transition state.
Palladium(II)-catalyzed claisen rearrangement of allyl vinyl ethers
作者:J.L van der Baan、F Bickelhaupt
DOI:10.1016/s0040-4039(00)85449-0
日期:1986.1
The Claisen rearrangement of allyl vinyl ethers is catalyzed by PdCl2(CH3CN)2, provided that alkyl substituents protect the vinyl ether double bond from coordination by the metal catalyst.
Horner-Emmons cyclization. Opticallyactive 3-H-1-carbacephem compounds were efficiently prepared by employing a penicillin acylase-producing microorganism in two ways. That is, the 7-phenylacetamide of a racemic carbacephem nucleus was hydrolyzed enantioselectively with the enzyme to afford the optically pure nucleus, which was then acylated to give antimicrobial compounds. Alternatively, a racemic
Synthetic studies on arene-olefin cycloadditions-VIII. Total syntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene
作者:Paul A Wender、Sunil K Singh
DOI:10.1016/s0040-4039(00)98278-9
日期:1985.1
Totalsyntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene are described in which a new element of stereoinduction in arene-olefin meta cycloadditions was tested and a new method for cycloadduct transformation was developed.