Resolution and configurational assignment of 3,4,5,6-tetrahydro-2-methyl-2,6-methano-2H-1-benzoxocine derivatives
Abstract
Chemical resolutions of the rigid, tricyclic 3,4,5,6-tetrahydro-2-methyl-2,6-methano-2H-1-benzoxocin-4-one (6) of biological and chiroptical interest have been performed. The configurational assignment was made by X-ray analysis and chemical correlation of its ketal (+)-9a synthesized with (2R,3R)-butane-2,3-diol. Kinetic resolution of the hydroxy derivative rac-10 by means of lipase from Pseudomonas cepacia proved the most effective procedure for resolution. The stereochemistry of the faster reacting enantiomer (+)-10 was deduced by chemical correlation with the ketal (+)-9. Model compounds (+)-1 and (−)-1 for chiroptical study of the chromane chromophore were also prepared.