Intramolecular carbolithiation reactions for the synthesis of 2,4-disubstituted tetrahydro-quinolines: evaluation of TMEDA and (-)-sparteine as ligands in the stereoselectivity.
The preparation of 4-substituted 2-phenyltetrahydroquinolines from N-alkenylsubstituted 2-iodoanilines via intramolecular carbolithiation reactions has been investigated. The stereochemical outcome of the carbolithiation reactions depends on the nature of organolithium employed to perform the lithium-halogen exchange, the solvent, or the use of additives, for example, TMEDA or chiral bidentated ligands such as (-)-sparteine. Thus, the 2,4-disubstituted tetrahydroquinolines are obtained with moderate diastereoselectivities (up to 77:23) and with ee up to 94% when Weinreb amide derivatives are used (R = CONMe(OMe)).
Martínez-Estíbalez
Unai
U
Departamento de Química Orgánica II, Facultad de Ciencia y Tecnología, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Apdo. 644. 48080 Bilbao, Spain.
Sotomayor
Nuria
N
Lete
Esther
E