Claisen rearrangement of meta-substituted allyl phenyl ethers
作者:J. Malcolm Bruce、Yusuf Roshan-Ali
DOI:10.1039/p19810002677
日期:——
Electron-releasing substituents at the 3-position of allylphenylethers favour Claisenrearrangement of the allyl group to the 6-position, whereas electron-acceptors favour migration to the 2-position. 2-Acylhydroquinone 4-allyl ethers yield, predominantly, the 3-allyl isomers, probably because internal hydrogen bonding confers naphthalenoid character on the aryl residue.
Trifluoroacetic acid catalysed Claisen rearrangement of 5-allyloxy-2-hydroxybenzoic acid and esters: an efficient synthesis of (±)-mellein
作者:Laurence M. Harwood
DOI:10.1039/c39820001120
日期:——
5-Allyloxy-2-hydroxybenzoicacid (1a) and the esters (1b–f) in refluxing trifluoroaceticacid are smoothly converted into 3,4-dihydro-5,8-dihydroxy-3-methylisocoumarin (3) and the corresponding 4-alkoxycarbonyl 2,3-dihydro-5-hydroxy-2-methylbenzofurans (4a–f)via regioselective Claisenrearrangement to the 6-position of the aromatic nucleus with subsequent acidcatalysed cyclisation.