Abstract
(R)-O-Acetylmandelic
acid is an efficient chiral auxiliary for the resolution of racemic
1-aryl-1,2,3,4-tetrahydroisoquinolines 2 and 3 via crystallization of the corresponding
diastereomeric amides 5 and 7.
Acidic hydrolysis of (R,S)-O-acetylmandelylanilide 7b afforded
optically pure (>99% ee) (S)-1-(2-aminophenyl)-1,2,3,4-tetrahydroisoquinoline
(3b). Removal of the chiral auxiliary attached
to the tetrahydroisoquinoline nitrogen (amide 5a)
afforded partially racemized amine 2 both
under hydrolytic and reductive cleavage conditions. Brønsted
acid catalyzes migration of the chiral auxiliary from the isoquinoline
nitrogen to aniline (6a → 7a).
Key words
amides - chiral auxiliaries - chiral resolution - rearrangements - quinolines
References
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