The solvolysis of gibberellin A5 methyl ester toluene-p-sulphonate — a bicyclo[3,2,1]octane bridgehead derivative

Abstract

Three by-products from the preparation of gibberellin A₅ from gibberellin A₁ methyl ester are shown to be the methyl ether of gibberellin A₅ methyl ester, and 2α-chloro-2,3-dihydrogibberellin A₅ methyl ester and its methyl ether. The isolation of the 7-methyl ethers led to a study of the solvolysis of the toluene-p-sulphonate of gibberellin A₅ methyl ester. The approximate first order rate constant of this bicyclo[3,2,1]octane bridgehead ester is shown to be of the expected magnitude by comparison with rate constants calculated for 1-adamantyl, 1-bicyclo[2,2,2]octyl, and 1-bicyclo[2,2,1]heptyl toluene-p-sulphonates.