Epoxidation catalysts
The present invention generally relates to methods for the synthesis of catalysts, including epoxidation catalysts, and related compounds and catalyst compositions. Embodiments described herein may provide efficient processes for providing catalysts (e.g., epoxidation catalysts) in large quantities and using simplified methods.
1. A method for synthesizing a catalyst, comprising:
reacting a compound of Formula (I),
wherein:
R 1 and R 2 can be the same or different and each can be hydrogen, alkyl, or aryl, provided that when one of R 1 and R 2 is hydrogen, the other is alkyl or aryl;
R 3 is a protecting group;
R 4 is a protecting group that can be removed in the presence of an acid; and
R 5 , R 6 , R 7 , and R 8 can be the same or different and each can be hydrogen, alkyl, or aryl, to produce a compound of Formula (II),
2. A method as in claim 1 , wherein:
R 1 and R 2 are alkyl; and
R 5 , R 6 , R 7 , and R 8 are each hydrogen.
3. A method as in claim 1 , wherein R 3 and R 4 each comprise a silicon-containing protecting group.
4. A method as in claim 3 , wherein the protecting group is trimethylsilyl (TMS), tributylsilyl (TBS), tert-butyldiphenylsilyl (TBDPS), tert-butyldimethylsilyl (TBDMS) triisopropylsilyl (TIPS), [2-(trimethylsilyl)ethoxy]methyl (SEM), trimethylsilyl triflate, triethylsilyl triflate, or tri-t-butylsilyl triflate.
5. A method as in claim 3 , wherein the protecting group is tributylsilyl (TBS).
6. A method as in claim 1 , wherein the compound of Formula (I) has the structure,
7. A method as in claim 1 , wherein the compound of Formula (II) has the structure,
8. A method as in claim 1 , wherein the act of reacting comprises exposure to an acid.
9. A method as in claim 8 , wherein the acid is HClO 4 .
10. A method as in claim 8 , further comprising the act of neutralizing the acid.
11. A method as in claim 10 , wherein the act of neutralizing comprises exposure to a base.
12. A method as in claim 10 , wherein the act of neutralizing comprises exposure to an ammonium hydroxide solution.
13. A method as in claim 1 , further comprising exposing the compound of Formula (I) to a species capable of forming an acetal or a ketal.
14. A method as in claim 1 , further comprising exposing the compound of Formula (I) to a species capable of forming a cyclic ketal.
15. A method as in claim 1 , further comprising exposing the compound of Formula (I) to a fluoride-containing species.
16. A method as in claim 15 , wherein the fluoride-containing species is sodium fluoride (NaF) or tetra-n-butylammonium fluoride (TBAF).
17. A method as in claim 1 , wherein the act of reacting comprises:
(i) exposure to HClO 4 and acetone;
(ii) exposure to ammonium hydroxide solution; and
(iii) exposure to tetra-n-butylammonium fluoride (TBAF).
18. A method as in claim 1 , further comprising the act of exposing the compound of Formula (II) to an oxidant.
19. A method as in claim 18 , wherein the oxidant comprising a transition metal.
20. A method as in claim 18 , wherein the oxidant comprises ruthenium.
21. A method as in claim 1 , wherein the compound of Formula (II) is oxidized to produce a compound having the following structure,
22. A method as in claim 1 , further comprising synthesizing a compound of Formula (I) via an aldol reaction.
23. A method as in claim 22 , wherein the aldol reaction comprises:
reacting an aldehyde species having the formula,
with a carbonyl species having the formula.
24. A method as in claim 23 , wherein the aldehyde species has the following structure,
25. A method as in claim 23 , wherein the carbonyl species has the following structure,