adenosine

adenosiini puhekieltä A nucleoside derived from adenine and ribose, found in striated muscle tissue.
2001, Leslie Iversen, Drugs: A Very Short Introduction, Oxford, p. 82,

Caffeine acts as an antagonist at receptors in the brain for one of the chemical messengers called adenosine.

This reaction will replace all the adenosines with isosines.