title: 2,2- and 2,6-Diarylpiperidines by aryl migration within lithiated urea derivatives of tetrahydropyridines.
abstract: 2-Aryltetrahydropyridines formed by anionic cyclization or ring-closing metathesis were converted to their N'-aryl urea derivatives. Depending on the position of the unsaturation within the tetrahydropyridine ring, metalation by deprotonative lithiation or carbolithiation led to migration of the N'-aryl substituent to the 2- or 6-position via intramolecular nucleophilic attack of a benzylic organolithium on the aryl ring. The products are a range of 2,2-, 2,2,3-, and 2,6-polysubstituted piperidine derivatives. Related chemistry was observed in pyrroline homologues.
authors.affiliation: School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Tait
authors.forename: Sam
authors.initials: S
authors.lastname: Butterworth
authors.forename: Jonathan
authors.initials: J
authors.lastname: Clayden
mesh_terms: D003500:Cyclization; D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D010880:Piperidines / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D014508:Urea / Q000737:chemistry*
chemical_list: D010880:Piperidines; D011725:Pyridines; D011758:Pyrroles; C013231:pyrroline; D014508:Urea; D008094:Lithium