A novel synthesis of substituted pyrroles by a gold(I)-catalyzed cascade reaction has been developed. The reaction proceeded with an autotandem catalysis consisting of an initial addition of gold-acetylide to an acetal moiety and was followed by gold-catalyzed 5-endo-dig cyclization and aromatization. Gold catalysts play a dual role in activating nucleophilicity or electrophilicity of terminal acetylenes by forming gold-acetylides or by π-coordination. The formal (3 + 2) annulation of two components provided a variety of substituted pyrroles in a modular fashion.
Autotandem Catalysis: Synthesis of Pyrroles by Gold-Catalyzed CascadeReaction. -New addition-cyclization sequence for the synthesis of multisubstituted pyrroles is reported. The reaction proceeds with an autotandem catalysis consisting of an initial addition of gold-acetylide to an acetal moiety and is followed by gold--catalyzed 5-endo-dig cyclization and aromatization. The advantage of this reaction is its versatility and convergency to synthesis of a variety of substituted pyrroles in a modular fashion by combination of two acyclic substrates with substituents installed beforehand. -(UEDA, H.; YAMAGUCHI, M.; KAMEYA, H.; SUGIMOTO, K.; TOKUYAMA*, H.; Org. Lett. 16 (2014) 18, 4948-4951, http://dx.doi.org/10.1021/ol5024695 ; Grad. Sch. Pharm. Sci., Tohoku Univ., Aoba, Sendai 980, Japan; Eng.) -C. Inoue 12-159
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