The Dimroth rearrangement of 9-substituted 1-methyladenines: accelerating effect of a beta-D-ribofuranosyl group at the 9-position.
The reaction rates of the Dimroth rearrangements of 9-substituted 1-methyladenines (1a-i) were measured in H2O at various pH's and ionic strength 1.0 at 40 degrees C. In all cases, attack of hydroxide ion on the protonated species of 1 at the 2-position was faster than that on the neutral species by a factor of 90-180. Among nine kinds of 9-substituents in these compounds, the beta-D-ribofuranosyl group was found to accelerate both modes of hydroxide attack most significantly. It has been concluded that this rate enhancement is attributable solely to the electron-withdrawing effect caused by the furanose ring oxygen and not to the 5'-hydroxy group, a potential participant in intramolecular catalysis for the hydroxide attack on the adenine ring at the 2-position.
D000225:Adenine / Q000031:analogs & derivatives*; D055598:Chemical Phenomena; D002621:Chemistry; D007700:Kinetics; D013329:Structure-Activity Relationship
C008407:1-methyladenine; D000225:Adenine