General one-pot, three-step methodology leading to an extended class of N-heterocyclic cations: spontaneous nucleophilic addition, cyclization, and hydride loss.
A new class of phenanthridinium derivative has been isolated from the reaction of 2-bromoethyl-phenanthridinium bromide with a range of primary amines in excellent yields. The reaction pathway is unprecedented and proceeds via three cascade steps: nucleophilic attack of a primary amine on the iminium moiety of a heteroaromatic ring system and cyclization to form a five-membered ring, followed by hydride loss to yield a rearomatized dihydro-1H-imidazo[1,2-f]phenanthridinium derivative. A range of NMR phase transfer experiments were carried out to elucidate the mechanistic pathway, and the methodology has been further developed by means of a biphasic system using N-bromosuccinimide as a co-oxidizing agent. The method has also been extended to other N-heterocyclic cation derivatives such as quinolinium and quinazolinium.
Parenty
Alexis D C
AD
Department of Chemistry, Joseph Black Building, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK.
Smith
Louise V
LV
Pickering
Alexandra L
AL
Long
De-Liang
DL
Cronin
Leroy
L