... The collected filtrates were evaporated to dryness to afford pure 6-cyanopurine IV. ... REFERENCES 1. For a review see: Shaw G. in: Comprehensive Heterocyclic Chemistry (AR Katritzky and A. W. Rees, Eds), Vol. 5, p. 550. Pergamon, Amsterdam 1984. ... 1389 Collect. Czech. ...