Some aspects of the chemistry of N(1)- and N(6)-dimethylallyl derivatives of adenosine and adenine

Abstract

N(1)- and N(6)-(3-Methylbut-2-enyl)adenosines have been perpared directly from adenosine. Treatment of the N(1)-isomer [obtained as the pure crystalline hydrobromide (IIa)] with N-hydrochloric acid gives first its aglycone (IX); this is then slowly dealkylated to give adenine. Contrary to reports in the literature, acidic hydrolysis of the N(6)-isomer (I) leads first to the simple aglycone (IV), which is then hydrated to give the N(6)-(3-hydroxy-3-methylbut-2-enyl) derivative (V). Under more vigorously acidic conditions, both (IV) and (V) are irreversibly converted into 3,7,8,9-tetrahydro-7,7-dimethylpyrimido[2,1-i]purine (VI). The isomeric 9,9-dimethyl tricyclic base (XI) has been prepared from (VI) by the Dimroth rearrangement. The mechanisms and biochemical significance of some of the reactions are considered.