Efficient synthesis of cytotoxic pyrido[1,2-e]purines from purines employing direct C-allylation and RCM–oxidation as key steps

Cytotoxic pyrido[1,2-e]purines are readily available from 8,9-diallylpurines by ring-closing metathesis (RCM) followed by oxidation. The 8,9-diallylpurines were synthesized conveniently by addition of allylmagnesium bromide to the corresponding C-8 unsubstituted purines, followed by rearomatization of the adducts.