Methods for producing hydroxy amino acids, esters, and derivatives thereof
A method for producing a hydroxy-amino ester, or derivative thereof, is provided. A substituted β-ketodiester having a ketone group and two ester functional groups is contacted with a ketoreductase under conditions permitting the reduction of the ketone group to an alcohol. Only one of the ester functional groups is regioselectively hydrolyzed to the corresponding carboxylic acid, whereby a non-hydrolyzed ester functional group remains. The carboxylic acid is converted to an amine or a derivative thereof to produce a hydroxy-amino ester or derivative thereof. A number of novel hydroxy-amino esters are prepared by the method.
1. A compound having the formula:
H 2 N—CHR 1 —CH(OH)—(CH 2 ) n —COOR 3
wherein n is 1; R 1 is allyl, propargyl, 4-pyridyl, isopropyl, propyl, or 2-thienyl; and R 3 is ethyl.
2. A method for producing a hydroxy-amino ester, comprising:
contacting a substituted β-ketodiester having a ketone group and two ester functional groups with a ketoreductase under conditions permitting the reduction of the ketone group to a hydroxyl group, said β-ketodiester having the formula: R 2 OOC—CHR 1 —CO—(CH 2 ) n —COOR 3 , wherein n is 1; R 1 is allyl, propargyl, 4-pyridyl, isopropyl, propyl, or thienyl; R 2 is selected from the group consisting of alkyl, substituted alkyl, aryl, substituted aryl, aralkyl, substituted aralkyl, heterocyclic, and substituted heterocyclic; and R 3 is ethyl;
regioselectively hydrolyzing one of the ester functional groups, R 2 OOC, to the corresponding carboxylic acid, whereby a non-hydrolyzed ester functional group, COOR 3 , remains; and
converting the carboxylic acid group to an amine to produce a hydroxy-amino ester corresponding to the compound recited in claim 1 .
3. The method of claim 2 , wherein the carboxylic acid is converted to an amine by the Curtius rearrangement.
4. The method of claim 3 , wherein the Curtius rearrangement is carried out using the reagent diphenylphosphoryl azide.
5. The method of claim 3 , wherein the Curtius rearrangement is carried out by converting the carboxylic acid to the corresponding acyl chloride and then reacting the acyl chloride with an azide salt.
6. The method of claim 5 , wherein the conversion of the carboxylic acid to the corresponding acyl chloride is carried out by reacting the carboxylic acid with oxalyl chloride.
7. The method of claim 2 , wherein the reduction of the ketone is substantially diastereoselective.
8. The method of claim 2 , wherein the hydroxyl group is protected prior to the conversion of the carboxylic acid to an amine.
9. The method of claim 2 , wherein the regioselective hydrolysis of only one of the ester functional groups to the corresponding carboxylic acid is catalyzed by an enzyme.
10. The method of claim 2 , wherein at least 90% of the one ester functional group is hydrolyzed to the corresponding carboxylic acid.
11. The method of claim 2 , wherein at least 95% of the one ester functional group is hydrolyzed to the corresponding carboxylic acid.