SYNTHESIS OF FLUORINATED (+ -)-PHORACANTHOLIDE AND RELATED-COMPOUNDS - REGIOSELECTIVE ACCESS TO A NOVEL CLASS OF MONOFLUORINATED FATTY-ACIDDERIVATIVES/

10-Fluorodecan-9-olide (1a), a monofluorinated analogue of (+/-)-phora cantholide, is synthesised in 20% overall yield by a five-step sequenc e starting with 9-decenoic acid (3a). 10-Undecenoic acid (3b) is trans formed in 28% overall yield into the next higher homologue, 11-fluorou ndecan-10-olide (1b). Their regioisomers, 9-fluorodecan-10-olide (2a) and 10-fluoroundecan-11-olide (2b), are obtained analogously in 20% or 29% yield. Key step of these syntheses is the regioselective opening of the epoxides of unsaturated fatty acid esters 5a and 5b.