Rhodium(II)-catalyzed decomposition of 3-O-(2-diazo-2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-D-allofuranose: diastereoselective ether formation.
Standard diazo transfer to 3-O-(2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-d-allofuranose (2), using p-acetamidobenzenesulfonyl azide (p-ABSA, 3) and DBU as base, provides the expected 3-O-(2-diazo-2-phenylacetyl)-1,2;5,6-di-O-isopropylidene-alpha-D-allofuranose (4) as an orange syrup in 49% isolated yield. Subsequent decomposition of 4 using Rh(2)(OAc)(4) yields ether 5 in a highly diastereoselective manner and in 58% isolated yield. The X-ray crystal structure of 5 proves that both newly produced stereocenters have the (S) configuration; the conformation of the ester group at O-3 of the furanose ring of 5 is used to discuss the possible cause of the observed stereoselectivity.
Sacui
Iulia A
IA
Department of Chemistry, Youngstown State University, Youngstown, OH 44555, USA.
Zeller
Matthias
M
Norris
Peter
P
D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D004987:Ethers / Q000138:chemical synthesis*; D006027:Glycosides / Q000737:chemistry*; D008968:Molecular Conformation; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
C531226:3-O-(2-diazo-2-phenylacetyl)-1,2-5,6-di-O-isopropylideneallofuranose; D001391:Azo Compounds; D004987:Ethers; D006027:Glycosides; D012238:Rhodium