Investigation of the synthesis and thermal rearrangements of 1,2,3,4,5-Pentaphenyl-2,4,-Cyclopentadiene Alkyl Ethers

Abstract

A comparative synthetic study of a series of six 1,2,3,4,5-pentaphenyl-2,4-cyclopentadiene alkyl ethers was investigated. It was determined that the most efficient route to these ethers was not the most generally accepted route to ethers - the Williamson Reaction - but rather a solvolysis reaction between 1-bromo-1,2,3,4,5-pentaphenyl-2,4-cyclopentadiene and the appropriate alcohol. Thermal rearrangement of the ethers had been expected to rearrange by a [1,5]-sigmatropic shift of the phenyl group in the 1-position to yield the corresponding enol ether. However, this appeared to occur only as a trace in some cases. Rather, the major product of the thermal rearrangements of these ethers was actually the elimination product, the hydrocarbon, 1,2,3,4,5-pentaphenyl-2,4-cyclopentadiene. The elimination is most likely the result of a retro-ene reaction.