Design, Synthesis, and Biological Activities of Some Branched Carbasugars: Construction of a Substituted 6-Oxabicyclo[3.2.1]nonane Skeleton

Transformation of c-yclohexa-2,4-diene-1,2-diylbis(methylene) diacetate to various carbasugars is described. Photooxygenation of a cyclohexadiene derivative gave a bicyclic endoperoxide, which was reduced with thiourea to [2-Racetyloxy)methyl]cyclohexa-2,4-dien-l-yl]methyl acetate. Epoxidation of the remaining double bond followed by epoxide ring-opening and hydrolysis of the acetate groups gave one of the target hexols. The bicyclic endoperoxide was rearranged to a diepoxide with CoTPP. The diepoxide was reacted with sulfamic acid in acetic anhydride, resulting in the formation of a new branched carbasugar as well as in the formation of cyclitols with a 6-oxabicyclo[3.2.1]nonane skeleton. The mechanism of the formation of the products is discussed. The inhibition activity of six cyclitol derivatives was tested against a-glycosidase.