C - Chemistry – Metallurgy – 07 – D
Patent
C - Chemistry, Metallurgy
07
D
260/286
C07D 217/20 (2006.01)
Patent
CA 1145753
Abstract of the Disclosure: The invention provides a novel method for the racemization of an optically active isomer, particularly the d-isomer, of a tetrahydroisoquinoline derivative of the formula: Image (I) wherein Ar is a trimethoxyphenyl group. This enables the enantiomorph (i.e. the d-isomer) which remains after sub- jecting a racemic modification of a tetrahydroisoquinoline derivative (I) to optical resolution and removing the desired optically active species (i.e. the ?-isomer), to be utilized. The racemization method comprises the steps of (a) acylating an optically active tetrahydroisoquinoline (I); (b) reacting the resulting optically active N-acyltetrahydroisoquinoline derivative (II) with an aralkyl halide; (c) hydrolyzing the resulting optically active N-acyltetrahydroisoquinoline derivative having protected hydroxy groups (III); (d) (1) subjecting the resulting optically active tetrahydroisoquino- line derivative having protected hydroxy groups (IV) to a halogenation reaction, followed by a dehydrohalogenation reaction, or (2) subjecting the optically active compound (IV) to nitrosation, followed by removal of hyponitrous acid; (e) reducing the resulting dihydroisoquinoline derivative having protected hydroxy groups (V); and then (f) subjecting the resulting racemic tetrahydroisoquinoline derivative having protected hydroxy groups (IV) to catalytic reduction to give the desired racemic modification of a tetrahydroisoquinoline derivative (I).
384396
Iwakuma Takeo
Ohtsuka Hisao
Yamada Koichiro
Kirby Eades Gale Baker
Tanabe Seiyaku Co. Ltd.
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