Samarium(II) iodide mediated intramolecular homolytic substitution at selenium: Preparation of 5-seleno-D-pentopyranose sugars from common pentose starting materials
摘要:
Treatment of 2,3,4-tri-O-benzyl-5-benzylseleno-5-deoxyribose (9) with samarium(II) iodide in II-TF affords 2.3,4-tri-O-benzyl-5-deoxy-5-seleno-D-ribopyranose (10) in 50% isolated yield in a process most likely involving intramolecular homolytic substitution at the selenium atom. In a similar fashion, 2,3,4-tri-O-benzyl-5-deoxy-5-seleno-D-xylopyranose (16) and 2,3,4-tri-O-benzyl-5-deoxy-5-seleno-D-arabanopyranose (17) were prepared from analogous precursors in 21 and 12% yields respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.