Cesium fluoride-mediated Claisen rearrangements of phenyl propargyl ethers: Substituent effects of an ortho-alkoxy group on the benzene ring or modified propargyl residues

The expected 7-alkoxy-2-methylbenzo [b]furans were effectively given in the CsF-mediated Claisen rearrangement of phenyl propargyl ethers with an o-alkoxy substituent on the benzene ring. On the other hand CsF did not affect the production of the corresponding benzo[b]furans when ethers, carrying a propargyl residue modified by either 1,1-dimethyl or 3-ethoxycarbonyl functions, were used as substrates in the rearrangement.