Process for the preparation of sulfur-containing N-benzyl-amino acids and esters
AssigneeBoehringer Ingelheim GmbH
InventorBernard Bellegarde
Life of this patent
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Abstract
A process for the preparation of sulfur-containing N-benzyl-amino acids of the formula ##STR1## wherein X and Y, which may be identical to or different from each other, are each hydrogen or halogen; R.sub.1 is hydrogen or alkyl of 1 to 4 carbon atoms; R.sub.2 is hydrogen, alkyl of 1 to 3 carbon atoms, carboxy-lower alkyl or acyl; R.sub.3 is hydrogen or acyl; and n is 1 or 2; which comprises the steps of converting anthranilic acid or a halogenated anthranilic acid into the corresponding aldehyde, reacting the aldehyde with a compound of the formula ##STR2## wherein R.sub.1, R.sub.2 and n have the meanings previously defined, to form the corresponding Schiff's base, reducing the said Schiff's base, and recovering the reaction product.
Claims9
A process for the preparation of a compound of the formula ##STR6## wherein X and Y, which may be identical to or different from each other, are each hydrogen or halogen;
- R.sub.1 is hydrogen or alkyl of 1 to 4 carbon atoms;
- R.sub.2 is hydrogen, alkyl of 1 to 3 carbon atoms, carboxy-lower alkyl or lower aliphatic acyl;
- R.sub.3 is hydrogen or lower aliphatic acyl;
- and
- n is 1 or 2;
- which comprises the steps of
- (A) converting anthranilic acid or a halogenated anthranilic acid into the corresponding aldehyde by
- (a) reacting the optionally halogenated anthranilic acid with thionyl chloride to form the corresponding anthranilic acid chloride, reacting the acid chloride with a secondary amine to form the corresponding tertiary amide, and reducing the tertiary amide;
- or
- (b) reducing the optionally halogenated anthranilic acid to form the corresponding alcohol, and oxidizing the said alcohol with a metal oxide;
- (B) reacting the aldehyde with a racemic or optically active compound of the formula ##STR7## wherein R.sub.1, R.sub.2 and n have the meanings previously defined, to form the corresponding Schiff's base;
- (C) reducing the said Schiff's base;
- and
- (D) recovering the reaction product.
Dependencies are inferred from the claim text.