Asymmetric Syntheses of 3,4-Substituted Tetrahydroquinoline Derivatives by (-)-Sparteine-Mediated Dynamic Thermodynamic Resolution of 2-(α-Lithiobenzyl)-<i>N</i>-pivaloylaniline
(-)-Sparteine-mediated dynamic thermodynamic resolution of 2-(α-lithiobenzyl)-N-pivaloylaniline was investigated. A temperature- and concentration-controlled epimerization-substitution sequence provides a simple protocol for the preparation of a highly enantioenriched benzyl-substituted N-pivaloylaniline product (up to 98:2 er). Also, application of this simple methodology to asymmetric syntheses of 1,3,4- and 3,4-substituted tetrahydroquinoline derivatives is demonstrated.
Regioselective Synthesis of 3-Bromoquinoline Derivatives and Diastereoselective Synthesis of Tetrahydroquinolines via Acid-Promoted Rearrangement of Arylmethyl Azides
Regioselective synthesis of 3-bromoquinolinederivatives was achieved via a formal [4 + 2]-cycloaddition between N-aryliminium ion, generated from arylmethyl azides, and 1-bromoalkynes. This method could also be applied to other quinoline derivatives using appropriate alkynes. Moreover, the current strategy could be utilized for the diastereoselective synthesis of tetrahydroquinoline derivatives employing alkenyl