Selective deacylation of peracylated ribonucleosides

A protocol for chemoselective deprotection of N,O-acylated ribonucleosides has been developed. Peracylated pyrimidine ribonucleosides subjected to guanidinium nitrate and NaOMe in MeOH/CH2Cl2 at 0 °C undergo high yielding O-deacylation, while even more pronounced chemoselectivity is observed with peracylated purine ribonucleosides as O5′-acyl groups are preserved. Nucleobase-protecting groups (ABz, CBz, GiBu, and UBz) are stable to these conditions, rendering this reagent mixture as a valuable addition to the collection of protecting group protocols in nucleoside chemistry.