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Sulfonyl Group Dance: A Tool for the Synthesis of 6‑Azido-2-sulfonylpurine Derivatives

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posted on 13.03.2020, 14:06 by Ja̅nis Miķelis Zaķis, Kristers Ozols, Irina Novosjolova, Reinis Vilšķe̅rsts, Anatoly Mishnev, Ma̅ris Turks
9-Substituted 2-chloro-6-sulfonylpurines provide 6-azido-2-sulfonylpurine derivatives with 61–83% yields when treated with sodium azide. Under optimized reaction conditions, the title compounds are obtained in a one-pot process, which involves a sequential treatment of 2,6-dichloropurines with a selected sodium sulfinate and sodium azide. Such a sulfonyl group dance (functional group swap) results from a cascade of SNAr reactions, which are facilitated by azidoazomethine-tetrazole (azide-tetrazole) tautomeric equilibrium. The formation of Meisenheimer-type intermediates as tetrazolopurine tautomers was supported by various spectroscopic methods, including 15N NMR.