Iron (III)-promoted aza-Prins-cyclization: direct synthesis of six-membered azacycles

RM Carballo, MA Ramírez, ML Rodríguez…

Index: Carballo, Ruben M.; Ramirez, Miguel A.; Rodriguez, Matias L.; Martin, Victor S.; Padron, Juan I. Organic Letters, 2006 , vol. 8, # 17 p. 3837 - 3840

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Citation Number: 106

Abstract

A new iron (III) halide-promoted aza-Prins cyclization between γ, δ-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of γ-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon-carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4- halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization ...