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

Transformation of cyclohexa-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-[(acetyloxy)­methyl]­cyclohexa-2,4-dien-1-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 α-glycosidase.