O-Heterocycles-Fused Indoles via Tandem 1,2-Indole Migration-Hydroxycyclization Reactions in
Lorena Renedo1, Marta Solas1, Carlos Silva López2
1Área de Química Orgánica, Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Pza. Misael Bañuelos s/n, 09001-Burgos, Spain.
Abstract:
Gold(I)-catalyzed tandem cyclization reactions of 3-propargylindoles bearing a hydroxyalkyl substituent at C2 enable rapid access to indole-fused cyclic ethers through the vinylogous reactivity of α,β-unsaturated gold-carbene intermediates. A selective intramolecular Michael-type attack of the hydroxyl group, supported by DFT studies, affords indole-fused six-, seven-, and eight-membered O-heterocycles under mild conditions. A one-pot hydrogen transfer process further delivers reduced pyranoindoles, highlighting the versatility and synthetic potential of this method.
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