Chemical Labeling of 5-Iodo-2′-deoxyuridine with 4-Ethynyl-N-ethyl-1,8-naphthalimide Using Copper-Free Sonogashira Cross-Coupling in Aqueous Medium

The utility of Sonogashira cross-coupling reactions in organic synthesis is indisputable. However, the palladium catalytic Sonogashira reaction in mild condition is still in its infancy. Here, we reported the synthesis of a fluorescent nucleoside analog by using a copper-free Sonogashira cross-coupling reaction in a satisfactory yield. This reaction occurred at 37 °C in the open air and aqueous medium, and avoided the toxicity of Cu(I). The mild Sonogashira reaction provided the possibility of fluorescent labeling of nucleoside mimics in living cells. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]