title: Facile one-pot synthesis of 2,3-dihydro-1H-indolizinium derivatives by rhodium(iii)-catalyzed intramolecular oxidative annulation via C-H activation: application to ficuseptine synthesis.
abstract: Various substituted indolizidinium, quinolizinium and pyrido[1,2-a]azepinium salts synthesized from benzaldehydes (or α,β-unsaturated aldehydes) and alkyne-amines catalyzed by rhodium complexes via C-H activation are demonstrated. The reaction was carried out under mild reaction conditions using Cu(BF4)2·6H2O as oxidant and anion source and inexpensive oxygen as a co-oxidant. A reaction mechanism involving imine formation followed by an ortho C-H activation, alkyne insertion and reductive elimination via a 7-membered rhodacycle is proposed. The present method has been successfully applied to the synthesis of a natural product, ficuseptine.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan. chcheng@mx.nthu.edu.tw.
authors.forename: Nitinkumar Satyadev
authors.initials: NS
authors.lastname: Upadhyay
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan. chcheng@mx.nthu.edu.tw.
authors.forename: Jayachandran
authors.initials: J
authors.lastname: Jayakumar
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan. chcheng@mx.nthu.edu.tw.
authors.forename: Chien-Hong
authors.identifier: http://orcid.org/0000-0003-3838-6845
authors.initials: CH
authors.lastname: Cheng