Purines protected at N-9 by p-methoxybenzyl are methylated or ethylated in 2,2,2-trifluoroethanol at N-7 by trimethyl- or triethyl-oxonium borofluorate, respectively. Subjecting the resulting cationic species to microwave irradiation releases an N7-methyl- or ethyl-purine. This one-pot procedure is an efficient regiospecific method applicable to diverse substrates.
Organic & Biomolecular Chemistry
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