Regioselective Sonogashira cross-coupling reactions of 6-chloro-2,8-diiodo-9-THP-9H-purine with alkyne derivatives

Lithiation of 6-chloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purine with LiTMP, gave access to 6-chloro-2,8-dihalogenated purine derivatives. In particular, the 6-chloro-2,8-diiodopurine derivative is an interesting new intermediate which gave regioselectively various 2-alkynylated compounds or 2,8-dialkynylated purines by using an excess of alkyne.