Process for the preparation of amphiphilic imidazolinium compounds
The present invention generally relates to improved processes for the preparation of amphiphilic imidazolinium compounds such as 1-[2-(9(Z)-octadecenoyloxy)ethyl]-2-(8(Z)-heptadecenyl)-3-(2-hydroxyethyl)imidazolinium chloride (DOTIM). In particular, the invention relates to processes for the synthesis of such compounds that avoid the need for toxic reagents, are more economical, and result in less waste than conventional methods. DOTIM and similar compounds can be formulated as cationic liposomes, which are useful as chemical vectors for nucleic acid delivery in gene therapy.
1. A process for preparing a compound of Formula (I)
wherein R is a straight-chain, aliphatic, saturated or unsaturated hydrocarbyl group of 11 to 29 carbon atoms, the process comprising: reacting a compound of Formula (II) with a hydrogen halide (HX) to provide a compound of Formula (III), wherein X is Cl, Br, or I;
reacting the compound of Formula (III) with a carboxylic acid halide [RC(O)Y], wherein R is as defined above for formula (I) and wherein Y is selected from the group consisting of Cl, Br, F, and I, or a carboxylic acid anhydride [RC(O)OC(O)R 2 ], wherein R is as defined above for Formula (I) and R 2 is a straight-chain or branched, aliphatic, saturated or unsaturated hydrocarbyl group of 1 to 29 carbon atoms, to provide a compound of Formula (IV); and
heating the compound of Formula (IV) to provide a compound of Formula (I)
2. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid halide [RC(O)Y], and X is not Cl and a compound of Formula (IVa) is provided, the process further comprising washing the compound of Formula (IVa) with an aqueous solution of sodium chloride to provide a compound of Formula (IVb)
3. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid anhydride [RC(O)OC(O)R 2 ], or the carboxylic acid halide [RC(O)Y] and X═Cl and a compound of Formula (IVb) is provided
4. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid halide or the carboxylic acid anhydride in the absence of an acid catalyst.
5. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid halide or the carboxylic acid anhydride in the absence of an acid catalyst selected from the group consisting of p-toluene sulfonic acid, benzenesulfonic acid, sulfoacetic acid, a phosphorus acid, and phosphorus trichloride.
6. The process of claim 1 , wherein the compound of Formula (II) is reacted with the hydrogen halide (HX) in a reaction mixture further comprising an organic solvent selected from the group consisting of C 2 -C 6 carboxylic acids, C 2 -C 6 nitriles, C 1 -C 6 alcohols, C 2 -C 10 ethers, C 3 -C 6 alkyl acetates, C 3 -C 10 ketones, C 5 -C 8 aliphatic hydrocarbons, C 1 -C 6 chlorinated hydrocarbons, C 3 -C 8 alkyl carbonates, sulfolane, dimethyl sulfoxide, toluene, chlorobenzene and combinations thereof.
7. The process of claim 1 , wherein the compound of Formula (II) is reacted with the hydrogen halide HX at a temperature from about 0° C. to about 60° C.
8. The process of claim 1 , wherein R 2 is a C 1 -C 10 straight-chain or branched aliphatic hydrocarbon.
9. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid halide [RC(O)Y], wherein R is a C 11 -C 29 straight-chain, aliphatic, hydrocarbyl group, and Y is Cl or Br.
10. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid anhydride [RC(O)C(O)R 2 ], wherein R is a C 11 -C 29 straight-chain saturated or unsaturated aliphatic hydrocarbyl group and R 2 is a C 1 -C 10 straight-chain or branched aliphatic hydrocarbyl group.
11. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid anhydride [RC(O)OC(O)R 2 ], or the carboxylic acid halide [RC(O)Y] in a reaction mixture further comprising an organic solvent selected from the group consisting of C 2 -C 6 nitriles, C 2 -C 10 ethers, C 3 -C 6 alkyl acetates, C 3 -C 10 ketones, C 5 -C 8 aliphatic hydrocarbons, C 1 -C 6 chlorinated hydrocarbons, C 3 -C 8 alkyl carbonates, sulfolane, dimethyl sulfoxide, toluene, chlorobenzene and combinations thereof.
12. The process of claim 1 , wherein the compound of Formula (III) is reacted with the carboxylic acid anhydride or the carboxylic acid halide at a temperature from about 0° C. to about 120° C.
13. The process of claim 3 , wherein a compound of the Formula (IV) wherein X is not Cl is contacted with an aqueous solution of sodium chloride to provide the compound of Formula (IVb).
14. The process of claim 13 , wherein the compound of Formula (IV) wherein X is not Cl is contacted with the aqueous solution of sodium chloride in a reaction mixture further comprising an organic solvent selected from the group consisting of C 2 -C 6 nitriles, C 2 -C 10 ethers, C 3 -C 6 alkyl acetates, C 3 -C 10 ketones, C 5 -C 8 aliphatic hydrocarbons, C 1 -C 6 chlorinated hydrocarbons, toluene, chlorobenzene and combinations thereof.
15. The process of claim 14 , wherein the compound of Formula (IV) wherein X is not Cl is contacted with an aqueous solution of sodium chloride at a temperature from about 0° C. to about 60° C.
16. The process of claim 2 , wherein the compound of Formula (IVb) is heated in a reaction mixture comprising the compound of Formula (IVb) and an organic solvent selected from the group consisting of C 2 -C 6 nitriles, C 1 -C 6 alcohols, C 2 -C 10 ethers, C 3 -C 6 alkyl acetates, C 3 -C 10 ketones, C 5 -C 8 aliphatic hydrocarbons, C 1 -C 6 chlorinated hydrocarbons, C 3 -C 8 alkyl carbonates, sulfolane, dimethyl sulfoxide, toluene, chlorobenzene and combinations thereof.
17. The process of claim 16 wherein the reaction mixture comprising the compound of Formula (IVb) further comprises a weak base selected from the group consisting of sodium bicarbonate, potassium bicarbonate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, a tertiary amine, and a mixture thereof.
18. The process of claim 16 , wherein the reaction mixture comprising the compound of Formula (IVb) and an organic solvent, further comprises a drying agent selected from the group consisting of molecular sieves, calcium chloride, magnesium sulfate, sodium sulfate, activated charcoal, and a combination thereof.
19. The process of claim 16 , wherein the reaction mixture comprising the compound of Formula (IVb) and the organic solvent is heated to a temperature from about 20° C. to about 100° C.
20. The process of claim 1 , wherein heating the compound of Formula (IV) forms a product mixture comprising the compound of Formula (I) and the process further comprises filtering the product mixture to form a solids fraction and a filtrate comprising the compound of Formula (I).
21. The process of claim 20 , wherein the compound of Formula (I) is recovered from the product mixture filtrate, and purified by washing with solvent, by recrystallization, or by a chromatographic method.
22. The process of claim 1 , wherein the compound of Formula (I) is 1-[2-(9(Z)-octadecenoyloxy)ethyl]-2-(8(Z)-heptadecenyl)-3-(2-hydroxyethyl)imidazolinium chloride (DOTIM):
23. A process for preparing a compound of Formula (I)
wherein R is a straight-chain, aliphatic, saturated or unsaturated hydrocarbyl group of 11 to 29 carbon atoms, the process comprising:
heating a compound of Formula (IV) in a reaction mixture comprising an organic solvent and a base to provide the compound of Formula (I)
wherein R is as defined above for Formula (I) and X is Cl, Br, or I.
24. The process of claim 23 further comprising washing a compound of Formula (IVa) wherein X is not Cl with an aqueous solution of sodium chloride to provide a compound of Formula (IVb), and the reaction mixture comprises a compound of Formula IV(b)
25. The process of claim 23 , wherein the base is a weak base selected from sodium bicarbonate, potassium bicarbonate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, a tertiary amine, or a mixture thereof.