Preparation of Anhydro-Thiohexofuranosides from Methyl Fructofuranosides Via the Thio-Mitsunobu Reaction¹

Abstract

Methyl α-D-fructofuranoside was transformed regioselectively into the corresponding 6-S-thioacetate in one step by use of the thio-Mitsunobu reaction. Reaction of the trimesylate derived from this thioacetate with sodium hydrogen carbonate led to the thietanosugar methyl 4,6-anhydro-1,3-di-O-mesyl-4-thio-α-D-tagatofuranoside. Methyl β-D-fructofuranoside gave the corresponding 6-S-thioacetate and, with excess thioacetic acid, the 1-S,6-S-bis-thioacetate. Whereas this mono-thioacetate did not yield a thietano derivative, the bis-thioacetate gave the bis-thietane methyl 1,3:4,6-dianhydro-1,4-dithio-β-D-sorbofuranoside with sodium hydrogen carbonate.

Keywords:

• Cyclisation
• intramolecular reaction
• S_N2
• methyl fructofuranosides
• thietanosugars
• thio-Mitsunobu reaction

This article was previously published in Phosphorus, Sulfur, and Silicon and the Related Elements 180(2) without figures. It is now reprinted here with figures. The publisher apologizes for this error.

We thank the University of Hamburg and the Fonds der Chemischen Industrie for financial support K. P. thanks the University of Hamburg for a Graduate Fellowship.

Notes

*The preparation of methyl fructofuranosides from 1 by use of I₂ in methanol has been described by W. A. Szarek, A. Zamojski, K. N. Tiwari, and E. R. Ison, Tetrahedron Lett., 27, 3827 (1986), but the authors did not report the experimental details (amounts of 1 and of the reagents, separation of the anomers). Therefore, we explored and applied the acid-catalyzed methanolysis of 1.