DIFFERENT MECHANISMS OF ARALKYLATION OF ADENOSINE AT THE 1-POSITION AND N-6-POSITION

The eight products resulting from opening of either enantiomer of styrene oxide at the alpha- or beta-carbon by the 1- or N-6-positions of adenosine were prepared and their configurations assigned. These markers allowed the mechanism of aralkylation of adenosine by styrene oxide to be investigated. It was found that formation of alpha-substituted products at the 1-position of adenosine involved total inversion of stereochemistry, whereas at the N-6-position inversion: retention was similar to 6:1. These differences in stereochemistry suggest that a more ionic form of styrene oxide is involved in N-6-aralkylation than in 1-aralkylation of adenosine. In the course of these studies, it was found that 1-substituted adenosines at the alpha- and beta-carbon of styrene oxide undergo Dimroth rearrangement at neutral pH and 37 degrees C and that the former compound also deaminates fairly readily under these conditions.