Facile Cu-free Sonogashira cross-coupling of nucleoside C-6 arylsulfonates with terminal alkynes

The combination of PdCl2[CH3CN]2 with XPhos is an efficient catalytic system for the Sonogashira-type cross-coupling of 2′-deoxyguanosine O6-arylsulfonates with terminal alkynes. The reactions generally proceed under mild conditions requiring no Cu co-catalyst to give the corresponding C-6-alkynylated deoxynucleosides in moderate to good yields.