Palladium-catalyzed cross-coupling of 2-iodoadenosine with terminal alkynes: synthesis and biological activities of 2-alkynyladenosines.

Reaction of 2-iodoadenosine (2) with terminal alkynes in the presence of bis (triphenylphosphine) palladium dichloride and cuprous iodide in triethylamine and N, N, -dimethylformamide gave 2-alkynyl-adenosines (3a-h) in excellent yields. Several compounds showed high activity as inhibitors in rat passive cutaneous anaphylaxis (PCA) reaction. Among them, 2-(3-hydroxypropynyl)- and 2-(3-hydroxybutynyl)-adenosines (3d, f) are much more potent than disodium cromoglycate (DSCG).