SYNTHETIC MICROBIAL CHEMISTRY, .25. SYNTHESIS OF THE ENANTIOMERS OF DIFFEROLIDE ANYL)-3A,4,5,6-TETRAHYDRO-1(3H)-ISOBENZOFURANONE], A MICROBIAL BIOREGULATOR FOR THE FORMATION OF AERIAL MYCELIUM AND SPORES OF STREPTOMYCES-GLAUCESCENS

Both the enantiomers of differolide uranyl)-3a,4,5,6-tetrahydro-1(3H)- isobenzofuranone (1)] were synthesized by starting from the known lact one rac-2. The key step was the optical resolution of hemiacetal rac-3 by acetal formation with (+)- or (-)-menthol. A single crystal X-ray analysis of acetal (-)-4a established its absolute configuration. Sinc e the natural product was known to be racemic, the present synthesis o f both (+)- and (-)-1 with known absolute configuration provided molec ular probes to examine the enantioselectivity at the receptor site of Streptomyces glaucescens.