Copper catalyzed cycloaddition of organic azides and 1-haloalkynes
This invention provides a method for preparing a 1,2,3-triazole compound comprising contacting an organic azide with a 2-substituted-1-haloalkyne, in the presence of a copper catalyst and a copper-coordinating ligand (preferably a tertiary amine) in a liquid reaction medium, thereby forming a 1,4,5-substituted-1,2,3-triazole compound including a halo substituent at the 5-position of the triazole, the organic portion of the organic azide at the 1-position of the triazole, and the substituent of the 1-iodoalkyne at the 4-position of the triazole. A method for preparing 1-iodoalkynes is also provided.
1. A method for preparing a 1,2,3-triazole compound comprising contacting an organic azide with a 2-substituted-1-iodoalkyne in the presence of a copper catalyst and an copper-coordinating ligand in a liquid reaction medium, thereby forming a 1,4,5-substituted-1,2,3-triazole compound including a iodo substituent at the 5-position of the triazole, the organic portion of the organic azide at the 1-position of the triazole, and the substituent of the 1-iodoalkyne at the 4-position of the triazole; wherein the copper-coordinating ligand comprises one or more materials selected from the group consisting of an amine, a thiol or salt thereof, a sulfide, a disulfide, a thiophene, a thiazole, and a phosphine.
2. The method of claim 1 wherein the copper catalyst comprises a Cu(I) salt.
3. The method of claim 1 wherein the copper catalyst comprises cuprous iodide.
4. The method of claim 1 wherein the copper catalyst or a portion thereof is generated in situ by reduction of a Cu(II) salt.
5. The method of claim 1 wherein the copper catalyst or a portion thereof is generated in situ by oxidation of Cu(0).
6. The method of claim 1 wherein the copper-coordinating ligand comprises a tertiary amine ligand.
7. The method of claim 1 wherein the copper-coordinating ligand comprises a 1,2,3-triazole-substituted tertiary amine.
8. The method of claim 1 wherein the copper-coordinating ligand comprises triethylamine.
9. The method of claim 1 wherein the copper-coordinating ligand comprises tris((1-tert-butyl-1H-1,2,3-triazolyl)methyl)amine (TTTA) or tris((1-benzyl-1H-1,2,3-triazolyl)methyl)amine (TBTA).
10. The method of claim 1 wherein the liquid reaction medium comprises an aprotic organic solvent.
11. The method of claim 10 wherein the aprotic organic solvent comprises at least one liquid selected from the group consisting of an ether, an amide, a nitrile, a hydrocarbon, and a chlorinated hydrocarbon.
12. The method of claim 1 wherein the liquid reaction medium comprises an alcohol.
13. The method of claim 1 wherein the liquid reaction medium comprises water.
14. The method of claim 1 wherein the organic azide is contacted with at least a stoichiometric amount of the 1-iodoalkyne based on the molar amount of azide in the organic azide and the molar amount of alkyne in the 1-iodoalkyne.
15. The method of claim 1 wherein the organic azide is contacted with less than a stoichiometric amount of the 1-iodoalkyne based on the molar amount of azide in the organic azide and the molar amount of alkyne in the 1-iodoalkyne.
16. The method of claim 1 wherein the organic azide is contacted with greater than a stoichiometric amount of the 1-iodoalkyne based on the molar amount of azide in the organic azide and the molar amount of alkyne in the 1-iodoalkyne.
17. The method of claim 1 including the additional step of separating the 1,4,5-substituted-1,2,3-triazole compound from the copper-coordinating ligand and any copper-containing materials present.
18. The method of claim 1 including the additional step of isolating the 1,4,5-substituted-1,2,3-triazole compound from the liquid reaction medium.
19. The method of claim 1 including the additional step of contacting the 1,4,5-substituted-1,2,3-triazole compound with an arylboronic acid in the presence of a Pd(0) catalyst, thereby replacing the 5-iodo substituent of the triazole with the aryl portion of the arylboronic acid.
20. The method of claim 1 including the additional step of contacting the 1,4,5-substituted-1,2,3-triazole compound with a reducing agent to replace the 5-iodo substituent with a hydrogen.
21. The method of claim 1 wherein the organic azide comprises a polyethylene glycol substituent and the substituent of the 2-substituted-1-iodoalkyne comprises a protein.
22. The method of claim 1 wherein the organic azide comprises a protein substituent and the substituent of the 2-substituted-1-iodoalkyne comprises a polyethylene glycol group.
23. The method of claim 1 wherein the liquid reaction medium includes a reducing agent.
24. The method of claim 23 wherein the reducing agent comprises a thiol compound.
25. The method of claim 24 wherein the thiol compound comprises dithiothreitol (DTT).
26. The method of claim 1 wherein the liquid reaction medium includes a surfactant.
27. The method of claim 26 wherein the surfactant comprises sodium docecyl sulfate.
28. The method of claim 1 wherein the 1,4,5-substituted-1,2,3-triazole compound is represented by the formula