Process for the preparation of racemic and optically active 1,2,

Details Process for the preparation of racemic and optically active 1,2, Process for the preparation of racemic and optically active 1,2,

1992-01-21

1993-10-12

Dentz, Bernard

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D21726

Patent

active

052527387

ABSTRACT:
A process for the preparation of racemic and optically active 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is described, in which dihalo-o-xylylenes are cyclized to dicarboxylic acid esters in basic medium using dialkyl N-acylamidomalonates of the formula (CO.sub.2 R.sup.1).sub.2 CHNHCOR.sup.2, in which R.sup.1 is (C.sub.1 -C.sub.4)-alkyl and R.sup.2 is H, (C.sub.1 -C.sub.4)-alkyl or (C.sub.6 -C.sub.12)-aryl, decarboxylated by basic hydrolysis and subsequent acid work-up and then reacted in acid medium to give (D,L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, or dihalo-o-xylylenes are cyclized in basic medium to give the dicarboxylic acid esters and these are reacted directly without isolation in a one-pot process to give (D,L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, if desired the racemic 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is reacted with (-)menthol and p-toluenesulfonic acid to give (-)menthyl (D)- or (L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate, then the diastereomers are separated by column chromatography and subjected to basic hydrolysis to give (D)- or (L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, or (D,L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is esterified by means of benzyl alcohol and p-toluenesulfonic acid, reacted with D(-)mandelic acid to give benzyl (D)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (D)-mandelate and benzyl (L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (D)-mandelate or with L(+)mandelic acid to give benzyl (D)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (L)-mandelate and benzyl (L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (L)-mandelate and then the compounds obtained are separated into the optical antipodes by fractional crystallization in an inert solvent and the enantiomers (D)- or (L)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid are liberated by basic hydrolysis, the chiral auxiliary reagent being recovered.

REFERENCES:
patent: 4912221 (1990-03-01), O'Reilly et al.
Seebach et al., Liebigs Ann. Chem., (12) pp. 1215-1232 (1989).
Chemical Abstracts, vol. 5 (1911) p. 3423.
Chem. Ber. 44,2030 (1911).

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