Self-sacrificing acetylation observed during attempted desilylation of 1-[4-benzenesulfonyl-3-O-(tert-butyldimethylsilyl)-2-deoxy-5-O-methanesulfonyl-α-l-threo-pentofuranosyl]thymine

Desilylation of 1-[4-benzenesulfonyl-3-O-(tert-butyldimethylsilyl)-2-deoxy-5-O-methanesulfonyl-α-l-threo-pentofuranosyl]thymine (4) with Bu4NF/THF, when carried out at room temperature, gave four products. Among these, there were 1-[3-O-acetyl-4-benzenesulfonyl-2-deoxy-5-O-methanesulfonyl-α-l-threo-pentofuranosyl]thymine (7) and thymine. A possible reaction mechanism is proposed, which suggests the origin of 3′-O-acetyl group of 7 and thymine as well as structures of the other two products (9a and 9b).