A base-free bis-alkyl thiolation reaction of indoles with sulfinothioates under Pummerer-type conditions is described. Sulfinothioates, activated with 2,2,2-trifluoroacetic anhydride, are demonstrated to be an efficient thiolation reagent for wide applications. This approach enabled double C–H thiolation at the C2 and C3 of the indole in one pot. The mechanism studies suggested the thiolation was realized through the sulfoxonium salt rather than sulfenyl carboxylate.

A catalyst-free cross-dehydrogenative coupling reaction of purines and some azoarenes with dialkyl disulfides has been developed. This procedure provided a novel strategy to construct unsymmetrical disulfides through the α-heterocyclic functionalization of symmetrical dialkyl disulfides. The S−S bond was successfully tolerated in this transformation. The mild conditions and the broad scope of azoarenes indicated the potential application of this procedure.

A metal-free cross-dehydrogenation coupling method was established to synthesize N9 alkylated purine derivatives. Using PhI(OAc)2 as oxidants, versatile thioethers were successfully employed as alkylation reagents, Under optimized conditions, a variety...

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