Abstract:
1-(0- and m-Ohlorobenzoyl)isoquinolines have been synthesized by
two routes involving Reissert compounds. One route involves condensation
of 2-benzoyl-l,2-dihydroisoquinaldonitrile with the appropriate
chlorobenzaldehyde and the second involves rearrangement of the
appropriate Z-(chlorobenzoyl)-l,Z-dihydroisoquinaldonitrile under
basic conditions. The action of potassamide in anhydrous liquid ammonia
on both ketones gave unexpectedly N-(l-isoquinolyl)benzamide (67)
as the major product and the use of dibenzo-18-crown-6-ether 98%
substantially improved the yd..e.ld in the case of l-chloroketone. This
amide (67) exhibits unusual hydrogen bonding.
1-(o-chlorobenzoyl)-6,7-dimethoxyisoquinoline (79) was prepared in
very s,amll quantities by the route involving condensation of 2-benzoyll,
Z-dihydro-6,7-dimethoxyisoquinaldonitrile with o-chlorobenzaldehyde.
The poor yields are due to the instability of the anion of 2-benzoyl1,
Z-dihydro-6,7-dimethoxyisoquinaldonitrile. Attempted preparation of
the ketone (79) by rearrangement of 2-(o-chlorobenzoyl)-l,2-dihydro6,7-
dimethoxyisoquinaldonitrile under basic conditions yielded the
start~ng material (Reissert compound) and 6,7-dimethoxyisoquinoline.
The action of potassamide in anhydrous liquid ammonia on
l-(o-bromo-4,5-dimethoxybenzoyl)isoquinoline (85), which was prepared
by the route involving the condensation of 2-benzoyl-l,4-dihydroisoquinaldonitrile
with o-bromo-4,5-dimethoxybenzaldehyde, gave two products,
which have not yet been identified. The ketone (85) and its precursors
are interest~ng in that their 20 eV and 70 eV mass spectra do not show
molecular ions.
