Unexpected cycloreversion of a tosylated sugar oxetane under E2 conditions. The facile formation of 2-(2-furanyl)-1,3-dioxolane from a novel 2,5:4,6-dianhydro-L-idose derivative

Abstract

2,5:4,6-Dianhydro-3-O-p-toluenesulfonyl-L-idose ethylene acetal (4) was synthesized with the aim of studying its chemical behaviour in the presence of several basic agents (Bu4NF/MeCN, NaOMe/MeOH, KOBut/ButOH/THF, and NaH/DMSO). Treatment of 4 with sodium hydride in dimethyl sulphoxide at room temperature unexpectedly gave the 2-(2-furanyl)-1,3-dioxolane. The mechanism of the process presumably involved the initial conversion of 4 to the corresponding 2,3-unsaturated derivative 5, followed by a facile oxetane ring cycloreversion by the elimination of formaldehyde.

Keywords

• 2
• 5-anhydro-L-idose
• 2
• 5:4
• 6-dianhydro-L-idose
• sugar oxetanes
• cycloreversion