Claisen rearrangement of tropolone ethers. Part II.
Abstract
Thermal isomerisations of 3-methylbut-2-enyl ethers of tropolone and 3,5,7-trimethyltropolone proceed in refluxing n-nonane with migration of the ether residue to both 3- and 5-positions. Where enolisation of the resulting cyclo-heptadienediones cannot occur the 5,5-disubstituted cyclohepta-3,6-diene-1,2-dione predominates in the resulting equilibrium.