Les systèmes biphasiques. 3. Alkylation des purines en catalyse par transfert de phase

The phase transfer catalysed methylation of adenine gave selectively 9-methyladenine (98%), while benzylation yields 9-benzyladenine as the major product accompanied by very small amounts of the 3-isomer. Alkylation of xanthine, theobromine and theophylline by the same technique gave also the corresponding N-alkyl derivatives in high yields, with no other O-alkylated regioisomer. These alkylation procedures, owing to their simplicity and selectivity, constitute a considerable improvement upon the classical techniques.