REACTIVITY STUDIES IN THE SHIKIMIC ACID SERIES - THE SYNTHESIS OF RACEMIC METHYL 6-ALPHA-FLUOROSHIKIMATE

The regio- and stereo-selective epoxidation of methyl 3,4-dihydrobenzoate derivatives has been investigated. Perbenzimidic acid leads only to epoxides formed at the Δ1,2 bond. More electrophilic reagents such as MCPBA also give products of this type, as well as epoxides formed through attack at the Δ5,6 bond. Reactions of the 3,4-dihydrobenzoates with thiophenate anion have been undertaken as a means of protecting the Δ1,2 bond and thence controlling the regioselectivity of epoxidation. A synthesis of racemic methyl 6α-fluoroshikimate has been achieved through the ring-opening of an epoxide of methyl 3,4-dihydro-3,4-isopropylidenedioxybenzoate. © 1990.