Asymmetric syntheses of 3,4-substituted tetrahydroquinoline derivatives by (-)-sparteine-mediated dynamic thermodynamic resolution of 2-(α- lithiobenzyl)-N-pivaloylaniline
The absolute configuration of 6 was assigned, after its conversion into 7, by comparison of its optical rotation with that of an authentic compound, in the following literature: (a) Paquin, J.-F.; Stephenson, C. R. J.; Defieber, C.; Carreira, E. M. Org. Lett. 2005, 7, 3821.
Reaction of 2-(1-lithioethyl)-N-pivaloylaniline with tert-butyl bromoacetate under the same reaction conditions gave the substituted product in lower enantioselectivity (84:16 er) and yield (22%).
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(a) Kiau, S.; Discordia, R. P.; Madding, G.; Okuniewicz, F. J.; Rosso, V.; Venit, J. J. J. Org. Chem. 2004, 69, 4256.
The relative configuration of trans-11 was assigned by comparison of its NMR data with that of an authentic compound, in the following literature: (a) Beifuss, U.; Ledderhose, S. J. Chem. Soc., Chem. Commun. 1995, 2135.
(b) Katritzky, A. R.; Rachwal, B.; Rachwal, S. J. Org. Chem. 1995, 60, 7631. The relative configurations of 9, 10, 12, and 13 were assigned by analogy to the formation of trans-11.