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.