The synthesis of a menthol derivative of 2-aminopurine as a fluorescent DNA lesion

An efficient synthetic route to the phosphoramidite of a menthol functionalized guanosine analog is presented. Two procedures were executed for the key introduction of the 6′-allyl menthyl moiety. Stille vinylation on 6-O-tosylguanosine followed by cross-metathesis using an excess of allyl menthyl ether proved to be less efficient than a Stille coupling on the same tosylate using an advanced menthyl-allyl stannane derivative. Incorporation of the modified nucleoside using the phosphoramidite method into a DNA 50-mer proceeded uneventfully.