posted on 2014-08-15, 00:00authored byElma Mons, Martin J. Wanner, Steen Ingemann, Jan H. van Maarseveen, Henk Hiemstra
A series of 1-substituted 1,2,3,4-tetrahydroisoquinolines
was prepared
from N-(o-nitrophenylsulfenyl)phenylethylamines
through BINOL-phosphoric acid [(R)-TRIP]-catalyzed
asymmetric Pictet–Spengler reactions. The sulfenamide moiety
is crucial for the rate and enantioselectivity of the iminium ion
cyclization and the products are readily recrystallized to high enantiomeric
purity. Using this methodology we synthesized the natural products
(R)-crispine A, (R)-calycotomine
and (R)-colchietine, the synthetic drug (R)-almorexant and the (S)-enantiomer of
a biologically active (R)-AMPA-antagonist.