Nucleic Acid Related Compounds. 127. Selective N-Deacylation of N,O-Peracylated Nucleosides in Superheated Methanol1
摘要:
Solutions of peracylated adenosine, cytidine, and related nucleoside derivatives undergo selective N-deacylation upon heating at elevated temperatures (oil bath >= 105 degrees C) in methanol. An increase in the bulk of the N-acyl group has little effect on the rate of N-deacylation but increases the N/O selectivity ratio. Extended heating is required for N-deacylation with arylcarboxylic acid derivatives. Contamination with acidic or basic reagent residues is avoided.
The ozonation of 4-thiopyrimidine and 6-thiopurine nucleosides in presence of amines afforded selectively and under mild experimental conditions several cytidine and adenosine nucleosides. The same reaction carried out in presence of alcohols afforded O4- or O6-alkylated derivatives of the nucleosides.