Facile synthesis of 2′-O-cyanoethyluridine by ring-opening reaction of 2,2′-anhydrouridine with cyanoethyl trimethylsilyl ether in the presence of BF3•Et2O

In this Letter, a facile method for the synthesis of 2'-O-cyanoethyluridine, which is a key intermediate in the synthesis of fully and partially 2'-O-cyanoethylated oligoribonucleotides as well as unmodified oligoribonucleotides, was developed by the ring-opening reaction of 2,2'-anhydrouridine with 2-cyanoethyl trimethylsilyl ether in the presence of BF3 center dot Et2O in dimethylacetamide. The 2'-O-cyanoethyluridine 3'-phosphoramidite derivative was converted into the 2'-O-cyanoethyl-4-N-acetylcytidine 3'-phosphoramidite derivative by a series of reactions involving displacement of the 4-(1H-1,2,4-triazol-1-yl)uridine derivative with ammonia followed by acetylation. (C) 2007 Elsevier Ltd. All rights reserved.