Transformation of C4-Methyl Derivatives of Levoglucosenone to 2,5-Dihydrofurans. An Unexpected Intramolecular Oxacyclization

Abstract

The acid-catalyzed reaction of C⁴-methyl derivatives of levoglucosenone with ethanethiol and propane-1,3-dithiol was studied. The reaction takes a nontrivial route and involves intramolecular oxacyclization to form 2,5-dihydrofurans containing a thioacetal group at C⁵ in the side chain. The transformation provides a short way to synthesize chiral 2,5,5-trialkyl-substituted 2,5-dihydrofurans from levoglucosenone.