Enzymic asymmetrization in organic media: synthesis of unnatural glucose from cycloheptatriene.

Pseudomonas cepacia lipase mediated asymmetrization of a meso-3-O-protected 6-cyclohepten-1,3,5-triol using isopropenyl acetate as solvent produced optically pure monoacetate 2. Elaboration of 2 by stereoselective oxygenation of the ring system using the Rubottom reaction, diastereoselective reduction, and osmium tetroxide catalyzed cis hydroxylation lead to cycloheptanehexaol derivative 20. As cyclic polyol was transformed into an allylic alcohol which was subjected to ozonolysis followed by NaIO 4 diol cleavage to give L-glucose