Release of Ring Strain as Driving Force for Inversion of Stereochemistry – Application to the Synthesis of Ribopyranosides from Xylopyranosides

Abstract

By using a Swern oxidation–epimerization–reduction ­sequence it is possible to selectively epimerize any position in isopropylidene-protected xylopyranosides, thus forming arabinosides, ribosides, and lyxosides. The driving force for epimerization of position 3 (xylo to ribo) is the release of ring strain by going from a 1,2-trans-acetal to a 1,2-cis-acetal.

Key words

acetals - carbohydrates - isomerization - ring strain - ­stereoselective synthesis

• References

• 1a Kondo Y. Carbohydr. Res. 1982; 110: 339
• 1b Kishimoto T, Ikeda T, Karlsson O, Magara K, Hosoya S. J. Wood Sci. 2002; 48: 32
• 2 Siegbahn A, Aili U, Ochocinska A, Olofsson M, Rönnols J, Mani K, Widmalm G, Ellervik U. Bioorg. Med. Chem. 2011; 19: 4114
• 3 Greene TW, Wuts PG. M. Protective Groups in Organic Synthesis. John Wiley and Sons; New York: 1999: 207
• 4 Catelani G, Colonna F, Marra A. Carbohydr. Res. 1988; 182: 297
• 5 Tojo G, Fernandez M. Oxidations of Alcohols to Aldehydes and Ketones . Springer; Heidelberg: 2006: 153
• 6 Spartan ’10, Version 1.1.0; Wavefunction, Inc.: Irvine (CA, USA).
• 7 Ohlinger WS, Klunzinger PE, Deppmeier BJ, Hehre WJ. J. Phys. Chem. A 2009; 113: 2165
• 8 Anderson JE, Ijeh AI. J. Chem. Soc., Perkin Trans. 2 1994; 1965