Method of preparing salicylamides
View Patent ↗The present invention provides a fast, high yield method for preparing salicylamide intermediates. The method comprises reacting a C 4 or higher alkyl ester of salicylic acid or derivative thereof with at least one amine selected from the group consisting of monoalkylamines, dialkylamines, ammonia, and any combination of any of the foregoing in alcohol to yield the salicylamide. The C 4 or higher alkyl ester of salicylic acid or a derivative thereof is preferably prepared by reacting salicylic acid or a derivative thereof with a C 4 or higher alcohol in presence of at least one of sulfuric acid, a sulfonic acid, and a mineral acid. This process for preparing salicylamide intermediates from salicylic acid or derivative thereof generally has a cycle time of about 2 days, and yields about 95% of a 99% pure material. In comparison, when a C 3 or lower alkyl ester is used in lieu of the C 4 or higher alkyl ester, the process generally has a cycle time of 7–9 days and yields about 60% of a 95% pure material. Methods of preparing an alkylated salicylamide are also provided.
1. A method for preparing a salicylamide comprising the step of reacting a C 4 or higher alkyl ester of salicylic acid or a derivative thereof with 8-aminocaprylic acid in alcohol to yield the salicylamide.
2. A method for preparing an alkylated salicylamide comprising the steps of:
(a) reacting a C 4 or higher alkyl ester of salicylic acid or a derivative thereof with at least one amine selected from the group consisting of monoalkylamines, dialkylamines, ammonia, and any combination of any of the foregoing in alcohol to yield a first salicylamide; and
(b) alkylating the first salicylamide to form the alkylated salicylamide, wherein the alkylated salicylamide is selected from N-(5-chlorosalicyloyl)-8-aminocaprylic acid, N-(10-[2-hydroxybenzoyl]amino)decanoic acid, N-(8-[2-hydroxybenzoyl]amino)caprylic acid, or a salt thereof.
3. The method of claim 2 , wherein step (b) comprises:
(i) protecting and activating the first salicylamide to form a protected/activated salicylamide;
(ii) alkylating the protected/activated salicylamide with an alkylating agent to form a protected/activated alkylated salicylamide; and
(iii) deprotecting and deactivating the protected/activated alkylated salicylamide to form the alkylated salicylamide.
4. The method of claim 2 , wherein the alkylated salicylamide is N-(5-chlorosalicyloyl)-8-aminocaprylic acid or a salt thereof.
5. The method of claim 2 , wherein the alkylated salicylamide is N-(10-[2-hydroxybenzoyl]amino)decanoic acid or a salt thereof.
6. The method of claim 2 , wherein the alkylated salicylamide is N-(8-[2-hydroxybenzoyl]amino)caprylic acid or a salt thereof.
7. A method for preparing an alkylated salicylamide comprising the steps of:
(a) reacting salicylic acid or a derivative thereof with a C 4 or higher alcohol in the presence of at least one of sulfuric acid, a sulfonic acid, or a mineral acid to form a C 4 or higher alkyl ester of salicylic acid or a derivative thereof;
(b) converting the C 4 or higher alkyl ester into a first salicylamide;
(c) alkylating the first salicylamide to form the alkylated salicylamide; wherein the alkylated salicylamide is selected from N-(5-chlorosalicyloyl)-8-aminocaprylic acid, N-(10-[2-hydroxybenzoyl]amino)decanoic acid, N-(8-[2-hydroxybenzoyl]amino)caprylic acid, or a salt thereof.
8. The method of claim 7 , wherein step (b) comprises reacting the C 4 or higher alkyl ester with at least one amine selected from the group consisting of monoalkylamines, dialkylamines, ammonia, and any combination of any of the foregoing in alcohol to yield the first salicylamide.
9. The method of claim 7 , wherein step (c) comprises:
(i) protecting and activating the first salicylamide to form a protected/activated salicylamide;
(ii) alkylating the protected/activated salicylamide with an alkylating agent to form a protected/activated alkylated salicylamide; and
(iii) deprotecting and deactivating the protected/activated alkylated salicylamide to form the alkylated salicylamide.
10. The method of claim 8 , wherein the alkylated salicylamide is N-(5-chlorosalicyloyl)-8-aminocaprylic acid or a salt thereof.
11. The method of claim 8 , wherein the alkylated salicylamide is N-(10-[2-hydroxybenzoyl]amino)decanoic acid or a salt thereof.
12. The method of claim 8 , wherein the alkylated salicylamide is N-(8-[2-hydroxybenzoyl]amino)caprylic acid or a salt thereof.
13. The method of claim 8 , wherein the alkylated salicylamide is N-(4-methoxysalicyloyl)-8-aminocaprylic acid or a salt thereof.