Probing of PSE acetal protection for nucleoside chemistry

The use of phenylsulfonylethylidene (PSE) acetal as a new 3′,5′-bridged protecting group in nucleoside chemistry is reported. The PSE acetal demonstrates to be compatible with Lewis acids used in standard glycosylation reactions. In addition, a selective 2′-O-deacylation from a 3′,5′-O-(phenylsulfonyl)-2′-O-acetyl nucleoside can be achieved, giving access to subsequent chemical modifications in 2′ position. However, the PSE acetal cleavage surprisingly appeared to be purine/pyrimidine base dependent.