Sonogashira reactions of α- and β-1-ethynyl-2-deoxyribosides: synthesis of acetylene-extended C-nucleosides

An improved practical protocol for the synthesis of both anomers of 1-ethynyl-2-deoxiribosides 1 was developed. The Sonogashira coupling of ethynyldeoxyribosides 1 with various aryl- and heteroaryl halides was carried out under various conditions. It was found that the use of copper-free coupling protocols could reduce the oxidative dimerisation in favour of arylalkynyldeoxyriboside formation.