The aldose reductase inhibitor 2, 3-dihydro-6-fluorospiro [4H-l-benzopyran-4, 4 '-imidazo~ dine]-2 ', 5 '-dione was resolved into its enantiomers. Sorbinil, the S isomer, was found to be a better inhibitor of the enzyme in vitro and in vivo than the corresponding R isomer. X-ray ...