A previous paper2 has described the different behavior toward acid hydrolysis of amino groups in the 2-and 4-positions of certain pyrimidine derivatives. There is also a difference in the reactivity of amino groups in the 2-and 6-positions of the purine nucleus, most strikingly demonstrated by the selective action of nitrous acid. Fischer3 observed that the amino group of 2-amino-6-hydroxypurine (guanine) can be replaced by a hydroxyl group upon ...
