Utilization of Meso Substrates by Catalytic Asymmetrization Reaction

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The asymmetric olefin migration reaction catalyzed by the cationic Rh-complex ligated with chiral BINAP had been investigated. At the beginning, the diol and the analogus which were easily prepared from the cyclopentadiene and benzoquione were used as the substrates.The following facts were discovered during investigation :1) The optical yield was 43%, when the diol was used as the substrate.2) The almost perfect results were obtained, when the bis-siltl ethers were used.3) The optical yield does not related to the bulkiness of the silyl functional group.4) The bis-alkyl ethers did not bring about good enantiomeric excess.5) The bis-ester did not work at all.6) The course of the olefin migration was inversely between the diol and the bis-silyl ether.Next, this methodology was further applied to the 7-membered meso-ene-diol. The first enantiomeric synthesis of the tropane alkaloid, physoveruvine was achieved from the isomerized product.