Anellation Reactions of Pyranose Derivatives

The “push‐pull”‐activated pyranosidulose 1 reacts with acetylacetone and ethyl acetoacetate to give the methyl pyrano‐[2′,3′:7,8]pyrano[3,2‐D][1,3]dioxin‐9‐yl ketone 2a and the pyrano[2′,3′:7,8]pyrano[3,2‐D][1,3]dioxine‐9‐carboxylate 2b. Treatment of 1 with 1,3‐cyclohexanediones leads to the 1,3‐dioxino[5′,4′:3,4]pyrano[3,4‐B]chromen‐11‐ones 4a and 4b. Dialkyl benzo[7,8]pyrano[3,2‐D][1,3]dioxine‐7,9‐dicarboxylates 5a and 5b were obtained by reaction of ulose 1 with dialkyl 3‐oxoglutarates.