| Popis: |
(+)-(1R,4R)-Bicyclo[2.2.1]hept-5-en-2-one (7) was prepared in 78.5% yield by oxidative degradation of (+)-(1R)-endo-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (4) by using an improved procedure for the oxidation of the dianion of 4 with dioxygen. Dihydroxylation of 7 with osmium tetroxide furnished the cis exo addition product 8c and, via reversible retro aldol reaction, the trans isomer 8t which was characterized by X-ray crystal structure analysis. 8c was transformed in four reaction steps into the lactone 2 which is a known starting material for a synthesis of the antiviral antibiotic aristeromycin (1). 8t is a potential starting material for syntheses of carbocyclic analogues of arabinofuranosyl nucleotides, e.g., the antiviral agent cyclaradine (3). |
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