Synthesis of Potentially Biologically Active 6‐(1,3‐Butadiynyl)purines

1,3‐Alkadiynyl(trimethyl)silanes were prepared by the Negishi or Sonogashira reactions of bromoethynyl(trimethyl)silane with several terminal alkynes in 34–75% yield. However, the direct Hiyama coupling of these compounds with 6‐iodopurine derivatives has not been successful. Therefore, a modified Sonogashira reaction using TBAF or CsF for in situ removal of the trimethylsilyl group has been utilized. This methodology afforded the desired 6‐(1,3‐butadiynyl)purines in 47–87% yield.