Rearrangement of allylic azide and phenylthio groups of 3′-azido- or 3′-phenylthio-4′,5′-didehydro-5′-deoxyarabinofuranosyluridines

The reversible intramolecular [3,3]-sigmatropic rearrangement between 1-(3-azido-3,5-dideoxy-beta-D-threo-pent-4-enofuranosyl) uracil (3) and 1-(5-azido-3,5-dideoxy-beta-D-glycero-pent-4-enofuranosyl)uraciI (4) and irreversible radical rearrangement of 1-(3,5-dideoxy-3-phenylthio-beta-threo-pent-4-enofuranosyl)uracil (5) and 1-[3,5-dideoxy-3-(4-tolyl)thio-beta-D-threo-pent-4-enofuranosyl]uracil (7) into 1-(3,5-dideoxy-5-phenylthio-beta-L-glycero-pent-4-enofuranosyl)uracil (6) and 1-[3,5-dideoxy-5-(4-tolyl)thio-beta-L-glycero-pent-3-enofuranosyl]uracil (8) were attained at room temperature. (c) 2005 Elsevier Ltd. All rights reserved.