Studies of nucleosides and nucleotides. 73. Chlorination of adenosine and its N6-methyl derivatives with t-butyl hypochlorite.

Adenosine was allowed to react with t-butyl hypochlorite in a variety of conditions. Using limited amount of the chlorinating agent at low temperature (-70°) a monochloro compound (IIa) was obtained. The structure of IIa was tentatively assigned as N6-chloroadenosine. When the chlorination was conducted at higher temperature using excess reagent in dimethylformamide (DMF), 8-chloroadenosine (IIIa) was obtained as the main product. The structure of IIIa was elucidated by ultraviolet, mass and nuclear magnetic resonance spectra together with their chemical reactivities. The chlorination of 2', 3', 5'-tri-O-acetyladenosine also afforded 8-chloro derivative (IIIb) which gave 8-chloroadenosine by the treatment with ammonia. When N6-methyl or N6-dimethyladenosine were chlorinated using t-butyl hypochlorite only in the former case N6-chloro compound (IIc) was obtained. 8-Chloro-N6-methyl and-N6-dimethyladenosine (IIIc, d) were obtained when the chlorination was conducted in DMF as the solvent using excess t-butyl hypochlorite.