Absence of reverse anomeric effect in furanosides

Summary, in English

A series of conformationally restricted N-"furanosides" has been synthesized, where the carbons of the tetrahydrofuran ring are kept in one plane by a rigid norbornane skeleton, permitting only the ring oxygen to move above or below the tetrahydrofuran ring plane. This causes the substituents of the anomeric carbon to occupy a pseudoaxial or a pseudoequatorial position. On protonation of these "norbornane-furanosides" with trifluoromethanesulfonic acid, all three compounds exhibited decreasing coupling constants for the anomeric proton, indicating a shift toward the pseudoaxial conformation. The coupling constant measurements were supported by volume integration of NOESY cross-peaks, which also showed a change toward the pseudoaxial conformation upon protonation of the nitrogen. These results provide no evidence for the so-called reverse anomeric effect; on the contrary they are in full agreement with a small normal anomeric effect.

• Author: Hans Grundberg; Johan Eriksson-Bajtner; Karl-Erik Bergquist; Anders Sundin; Ulf Ellervik
• Department/s: Centre for Analysis and Synthesis
• Publishing year: 2006
• Language: English
• Pages: 5892-5896
• Publication/Series: Journal of Organic Chemistry
• Volume: 71
• Issue: 16
• Links: http://dx.doi.org/10.1021/jo060436i
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Organic Chemistry
• Status: Published
• ISBN/ISSN/Other: ISSN: 1520-6904