The topochemical synthesis of triazole-linked homobasic DNA

Triazolyl-DNA (TLDNA), DNA wherein phosphodiester units are replaced by triazole units, is of great interest. By adopting Topochemical Azide–Alkyne Cycloaddition (TAAC) reaction, we have synthesized homobasic TLDNA oligomers. 5′-ethynyl-3′-azido-2′,3′,5′-tri-deoxycytosine, which crystallized with proximal placement of azide and alkyne units of adjacent molecules, underwent TAAC reaction to TLDNA oligomers.</p

Sulfonylative and azidosulfonylative cyclizations by visible-light-photosensitization of sulfonyl azides in THF

The generation of sulfonyl radicals from sulfonyl azides using visible light and a photoactive iridium complex in THF is described. This process was used to promote sulfonylative and azidosulfonylative cyclizations of enynes to give several classes of highly functionalized heterocycles. The use of THF as the solvent is critical for successful reactions. The proposed mechanism of radical initiation involves the photosensitized formation of a triplet sulfonyl nitrene, which abstracts a hydrogen atom from THF to give a tetrahydrofuran-2-yl radical, which then reacts with the sulfonyl azide to generate the sulfonyl radical