Electrophile-induced bromocyclization of gamma,delta-unsaturated ketimines to intermediate 1-pyrrolinium salts and their selective conversion into novel 5-alkoxymethyl-2-aryl-3-chloropyrroles and 2-aroylpyrroles.
N-(1-Aryl-2,2-dichloropent-4-enylidene)amines were efficiently transformed into 5-bromomethyl-1-pyrrolinium bromides via electrophile-induced bromocyclization. The latter pyrrolinium salts were converted into novel 5-alkoxymethyl-2-aryl-3-chloropyrroles by reaction with alkoxides in the corresponding alcohol or in THF. This chemistry clearly deviates from the corresponding gamma,delta-unsaturated alpha,alpha-dialkylaldimines under similar conditions. Furthermore, treatment of 5-bromomethyl-1-pyrrolinium bromides with sodium hydroxide in water afforded a new entry into 2-aroylpyrroles by an unexpected ring transformation of intermediate aziridine derivatives, which could be isolated as well.
Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Belgium.
Matthias
M
D'hooghe
Christophe
C
Buyck
Jan
J
Contreras
Norbert
N
De Kimpe
D000588:Amines / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry*; D003500:Cyclization; D011758:Pyrroles / Q000737:chemistry*; D013379:Substrate Specificity
D000588:Amines; D011758:Pyrroles; D001966:Bromine