Abstract
A series of new o- and p-substituted 2-phenyl-ethanols 1 - 6 were synthesized and their usefullness as phosphate blocking groups in the triester approach of oligonucleotide synthesis studied with simple model substances. Various 5′-O-tritylthymidin-3′-o-chlorophenyl-ß-phenylethylphosphate triesters (8 - 13) were prepared and the conditions for selective cleavage of the phosphate protecting group worked out. The best combination so far has been found in 5′-O-trityl-thymidine-3′-o-chlorophenyl-ß-(2-chloro-4-nitrophenyl)-ethylphosphate (13) which could selectively be deblocked at each position.