| http://www.w3.org/ns/prov#value | - Chem., 11, 1872 (1979): ##STR3## where Q is NH or O.SUMMARY OF THE INVENTIONAn object of the present invention is to provide novel condensed purine derivatives represented by the formula (I): ##STR4## in which R.sup.3 represents hydrogen, lower alkyl or benzyl; each of X.sup.1 and X.sup.2 independently representshydrogen, lower alkyl, aralkyl or phenyl; and n is an integer of 0 or 1; R.sup.1 repre
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