An efficient method for the synthesis of pyranoid glycals

• Synthesis of pyranoid glycals using Zn/NH4Cl system.
• High yields and short reaction time.
• Simple operation and broad functional group compatibility.
• Efficient synthesis of glucal in gram-scale amount.

A simple and efficient procedure was designed for the preparation of pyranoid glycals. In a novel fashion, a series of protected glycopyranosyl bromides underwent reductive elimination in the presence of zinc dust and ammonium chloride in CH3CN at 30–60 °C. The corresponding glycals were obtained with excellent isolated yields (72–96%) in a short time (20–50 min). Furthermore, the transformation was compatible with different protection patterns and conveniently scalable (86% for 45 g acetobromoglucose) which made it very applicable in organic synthesis.

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