Hydrolysis and Rearrangement of O6-Substituted Guanosine Products Resulting from Reaction of Guanosine with Styrene Oxide

Article abstract of DOI:10.1021/jo00365a018

The preparation and properties of four diastereomeric O⁶-substituted guanosines which result from reaction between guanosine and styrene oxide are described.While the two diastereomers for O⁶-(2-hydroxy-2-phenylethyl)guanosine (1bI and 1bII) are reasonably stable under mildly acidic aqueous conditions, the two diastereomers for O⁶-(2-hydroxy-1-phenylethyl)guanosine (1aI and 1aII) undergo acid-catalyzed hydrolysis to cleave the O⁶-aralkyl ether linkage.In neutral and alkaline aqueous conditions 1aI and 1bI or 1aII and 1bII interconvert.An equilibrium is established between the isomers such that at equilibrium the ratio of 1bI/1aI or 1bII/1aII is 2.0.The rate of equilibration is first-order in hydroxide ion although the equilibrium constant is independent of pH over the range 7.5-12.The configuration about the α-carbon of the substituted phenylethyl side chain is retained during isomer equilibration.