Method for synthesizing novel chiral ligand, metal chelate, a variety of non-natural amino acids, maraviroc and key intermediate thereof
Disclosed is a method for synthesizing a novel chiral ligand, a metal chelate, a variety of non-natural amino acids, Maraviroc and a key intermediate thereof. In the invention, (R)-2-methyl proline is selected and used as a starting raw material, (S)-β 3 -amino acid is obtained by asymmetric resolution induced by using a nickel chelate, and Maraviroc is synthesized by using (S)-3-amino-3-phenylpropionic acid as a key intermediate with a high yield and the ee value reaching 98.2% or more. The method of the present invention has widely available materials, mild synthetic process conditions, is easy to control, and produces a product of a high optical purity.
1. A novel resolution method for an alpha amino acid, an alpha substituted beta amino acid and a beta substituted beta amino acid comprising the step of hydrolyzing a compound of formula VI to obtain the alpha amino acid, the alpha substituted beta amino acid and the beta substituted beta amino acid of formula VII,
wherein n is an integer from 1 to 4, m is an integer from 0 to 1;
R is selected from the group consisting of C1-C4 alkyl, C1-C4 haloalkyl and unsubstituted or substituted phenyl, wherein the substituted phenyl means that the phenyl has 1-5 substituents, and each substituent is independently selected from the group consisting of amino, halogen, hydroxyl, C1-C4 alkyl and C1-C4 haloalkyl;
R 1 is selected from the group consisting of H, C1-C4 alkyl, C1-C4 haloalkyl and unsubstituted or substituted phenyl, wherein the substituted phenyl means that the phenyl has 1-5 substituents, and each substituent is independently selected from the group consisting of amino, halogen, hydroxyl, C1-C4 alkyl and C1-C4 haloalkyl;
R 2 is selected from the group consisting of H, halogen, amino, hydroxyl, C1-C4 alkyl and C1-C4 haloalkyl;
R 3 is selected from the group consisting of H, C1-C4 alkyl, C1-C4 haloalkyl, unsubstituted or substituted phenyl and —(C1-C4 alkylene)-(unsubstituted or substituted phenyl); wherein the substituted phenyl means that the phenyl has 1-5 substituents, and each substituent is independently selected from the group consisting of amino, halogen, hydroxyl, C1-C4 alkyl and C1-C4 haloalkyl;
R 4 is selected from the group consisting of H, unsubstituted or substituted C6-C10 aryl, unsubstituted or substituted C3-C6 heteroaryl and unsubstituted or substituted C3-C6 cycloalkyl, wherein the “substituted” means that there are 1-5 substituents, and each substituent is independently selected from the group consisting of amino, halogen, hydroxyl, nitro, cyano, C1-C4 alkyl, C1-C4 alkoxy and C1-C4 haloalkyl;
R 5 is selected from the group consisting of H, unsubstituted or substituted C6-C10 aryl, unsubstituted or substituted C3-C6 heteroaryl and unsubstituted or substituted C3-C6 cycloalkyl, wherein the “substituted” means that there are 1-5 substituents, and each substituent is independently selected from the group consisting of amino, halogen, hydroxyl, nitro, cyano, C1-C4 alkyl, C1-C4 alkoxy and C1-C4 haloalkyl.
2. The resolution method of claim 1 , wherein the compound of VI is synthesized by the following step:
reacting a compound of formula IV with an unnatural amino acid of formula V under the action of a nickel salt to form the compound of formula VI,
wherein n, m, R, R 1 , R 2 , R 3 , R 4 and R 5 are as defined in claim 1 .
3. A Maraviroc intermediate having a structure of formula VI:
wherein n, m, R 1 , R 2 , R 3 , R 4 an R 5 areas defined in claim 1 .
4. The resolution method of claim 2 , wherein the compound of IV is synthesized by the following step:
(i) reacting (R)-2-substituted proline with di-tert-butyl dicarbonate to form (R)-1-(tert-butoxycarbonyl)-2-methylproline;
(ii) subjecting (R)-1-(tert-butoxycarbonyl)-2-substituted proline to a condensation reaction with a compound of formula I to obtain a compound of formula II;
(iii) removing tert-butoxycarbonyl from the compound of formula II to obtain a compound of formula III;
(iv) subjecting the compound of formula III to a reductive amination reaction with R 3 CHO or R 3 CH 2 Cl to obtain a compound of formula IV,
wherein n, R, R 1 , R 2 and R 3 are as defined in claim 1 .