Synthesis of Heptano Bridged Pyranoside Derivatives

Abstract

Addition of dichlorocarbene to the glycal (±±)‐2 followed by cyclopropyl‐allyl rearrangement leads to the chloro‐2H‐pyran (±±)‐4. Oxidation of (±±)‐4 and reduction of the obtained hydroxypyranone (±±)‐5 gave the methyl pyranoside (±±)‐6. The relative configuration of (±±)‐6 was established by X‐ray structural analysis of the corresponding acetate (±±)‐7. The synthesis of the optically active starting materials (+)‐2 and (−)‐2 is also reported.