Rare Gold-Catalyzed 4-exo-dig Cyclization for Ring Expansion of Propargylic Aziridines toward Stereoselective (Z)-Alkylidene Azetidines, via Diborylalkyl Homopropargyl Amines

Identifier:  imarina:9380067

Handle: https://hdl.handle.net/20.500.11797/imarina9380067

Authors:  Salvado, Oriol; Perez-Ruiz, Jorge; Mesas, Alba; Diaz-Requejo, M Mar; Rerez, Pedro J; Fernandez, Elena

Abstract:
We report an uncommon 4-exo-dig cyclization of N-tosyl homopropargyl amines, catalyzed by [AuCl(PEt3)]/AgOTf, to prepare stereoselective (Z)-2-alkylidene-1-tosylazetidine compounds. The reaction outcome contrasts with the gold-catalyzed cyclization of N-tosyl homopropargyl amines containing a methyl group at the propargylic position that provides substituted 2,3-dihydropyrroles via a 5-endo-dig mechanism. The access to N-tosyl homopropargyl amines is possible by the regioselective nucleophilic attack of alpha-diboryl alkylidene lithium salts to propargylic aziridines.