The Preparation of 4′,6′-Di- and 2′,4′,6′-Tri-O-acetates of Theophylline Nucleosides of 3′-Deoxy-3′-nitro-β-d-galacto-, gluco- and mannopyranose

Abstract

Abstract 7-(3′-Deoxy-3′-nitro-β-d-glucopyranosyl)theophylline (1) was treated with acetic anhydride in the presence of boron trifluoride, perchloric or phosphoric acid as a catalyst to afford the corresponding 2′,4′,6′-tri-O-acetate (4) in 87, 60 and 48% yields, respectively. With galacto-isomer (2), tri-O-acetate (6) was obtained in a high yield by the use of phosphoric acid or a large excess of perchloric acid as a catalyst, while 4′,6′-di-O-acetate (5) was selectively prepared in 82% yield when a trace of perchloric acid was used. The similar preparation of 4′,6′-di- and 2′,4′,6′-tri-O-acetates (7 and 8) of manno-isomer (3) was also carried out in the presence of boron trifluoride and phosphoric acid, respectively. The positions of the acetyl groups in the diacetates 5 and 7 were unequivocally deduced from NMR data.