Biotransformations of bicyclic trimethylcyclohexane chloro-, bromo- and iodolactones using fungal strains

Several fungal strains (Fusarium, Botrytis, Beauveria) were screened for their ability to transform three bicyclic halo-gamma-lactones with a trimethylcyclohexane ring. Most of the micro-organisms carried out hydrolytic dehalogenation and transformed these lactones into two hydroxy-gamma-lactones: cis (-)-2-hydroxy-4,4,6-trimethyl-9-oxabicyclo[4.3.0]nonan-8-one and trans (+)-2-hydroxy- 4,4,6-trimethyl-9-oxabicyclo[4.3.0]nonan-8-one. The structures of all substrates and products were established on the basis of their spectral data and X-ray analysis. The method presented offers an alternative route to obtaining hydroxy-lactones with high enantiomeric excess.