Nucleosides. Part LXIII. Acetals as new 2?-O-protecting functions for the synthesis of oligoribonucleotides: Synthesis of uridine building blocks and evaluation of their relative acid stability
A broad variety of new acyclic vinyl ethers (see 6–41) have been synthesized via the vinyl-interchange reaction of ethyl vinyl ether at room temperature using mercury(II) trifluoroacetate as a highly efficient catalyst. The appropriate vinyl ethers were reacted under acidic conditions with 3′,5′-O-silyl-protected uridine 42 to the corresponding 2′-O-(1-alkoxyethyl) derivatives 43–83 which gave, on
The 1-(2-chloroethoxy)ethyl (Cee) group is completely stable under the acidic condition required to remove the 5′-protecting groups in oligonucleotide synthesis, but can be cleaved under the similar conditions to that of the tetrahydropyranyl (Thp) in the region of pH 2–3.