Cepstral channel normalization techniques for HMM-based speaker verification

Process for preparing 8,2'-O-anhydropurine nucleosides having a utility as intermediates for antiviral and anticarcinogenic drugs which comprises heating 2',3'-O-sulfinyl-8-oxypurine nucleosides in an aprotic polar solvent in the presence of an alkali metal, alkaline earth metal or ammonium salt of an inorganic or organic weak acid.