A new one-pot preparation of polysubstituted imidazoles by a Staudinger/aza-Wittig/Ag(I)-catalyzed cyclization/isomerization has been developed. The easily accessible propargylazide derivatives reacted with triphenylphosphine, isocyanates, and amines sequentially to produce the fully substituted imidazoles in good overall yields in the presence of catalytic amount of AgNO/DMAP.
Iminophosphoranes reacted with CS 2 at -5 °C to produce the isothiocyanates, which were treated with primary amine to give thioureas in 73-91% yields. The subsequent reaction of thioureas with alkyl bromides in the presence of solid K 2 CO 3 produced 2-alkylthiopyrimidin-4(3H)-ones in 68-88% yield via tandem intramolecular cyclization-isomerization-S-alkylation.
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