C‑4 Functional Group-Driven Stereodivergent Synthesis and Late-Stage Diversification of 6‑Deoxy l‑talo/gulo Rare Sugars

We report a modular and stereodivergent synthesis of 6-deoxy-l-talose and 6-deoxy-l-gulose rare sugars via chemoselective glycosylation and regioselective dihydroxylation. Judicious variation of the C-4 substitution precisely controlled diastereoselectivity, enabling complementary access to both epimers. Proof-of-principle and synthetic versatility were demonstrated with carbohydrates, amino acids, natural products, and bioactive molecules, affording diverse rare sugar analogs. Late-stage functionalization of custom-tailored glycosides generated a library of rare sugar conjugates, including ferrocene hybrids, medicinally valuable scaffolds, and therapeutic agents.