Abstract To an aqueous solution of D,L-N-benzoyl-3,4-dimethoxy-phenylalanine there is added at least one amine selected from the group consisting of D(-)-threo-1-m-nitrophenyl-2-amino-propanediol-1,3, D(-)-threo-1-p-nitrophenyl-2-amino-propanediol-1,3 and D(-)threo-1-phenyl-2-amino-propanediol-1,3 selectively to precipitate the amine salt of the L-stereoisomer which is separated, dissolved and acidified to precipitate the free L-stereoisomer which is saponified to L-3,4-dihydroxy-phenyl-alanine. The mother liquor from the initial precipitation containing the amine salt of the D-stereoisomer and some L-stereoisomer is acidified to precipitate the free stereoisomers, leaving the amine in the acidified solution. The precipitated free stereoisomers are racemized and recycled for recovery of additional L-stereoisomer. The acidified solution of amine is rendered alkaline and steps are taken to regenerate and recycle the free amine.
Process according to claim 1, wherein there is also added to said solution up to about 0.5 mole of sodium hydroxide per mole of D,L-N-benzoyl-3,4-dimethoxy-phenylalanine, the total of amine plus sodium hydroxide being substantially about 1 mole per mole of D,L-N-benzoyl-3,4-dimethoxy-phenyl-alanine.
Claim 2
Dependent Claim
10 words
Process according to claim 1, wherein said amine is D(-)-threo-1-m-nitrophenyl-2-amino-propanediol-1,3.
Claim 3
Dependent Claim
18 words
The L-N-benzoyl-3,4-dimethoxy-phenyl-alanine salt of at least one amine selected from the group consisting of D-(-)-threo-1-m-nitrophenyl-2-amino-propanediol-1,3, D-(-)-threo-1-p-nitrophenyl-2-amino-propanediol-1,3, and D(-)-threo-1-phenyl-2-amino-propanediol-1,3.
Claim 4
Dependent Claim
11 words
A salt according to claim 4, wherein said amine is D(-)-threo-1-m-nitrophenyl-2-amino-propanediol-1,3.