Process for the addition of thiolates to α,β-unsaturated carbonyl or sulfonyl compounds
View Patent ↗Alkylthio substituted aldehydes, ketones, esters and sulfones are prepared by reacting α,β-unsaturated carbonyl and sulfonyl compounds with a sodium or potassium thiolate in the presence of a alkane carboxylic acid and water.
1. A process for the preparation of alkylthio substituted aldehydes, ketones, and esters of formula I
wherein
E represents CO;
R 1 represents H, C 1 -C 8 alkyl, C 1 -C 8 alkoxy or aryl; and
R 2 , R 3 , R 4 and R 5 independently represent H, C 1 -C 8 alkyl or aryl which consists essentially of reacting an α,β-unsaturated carbonyl compound of the formula II
wherein
E, R 1 , R 2 , R 3 and R 4 are as previously defined with a sodium or potassium thiolate of formula III
R 5 S − Na + or K + (III)
wherein
R 5 is as previously defined
in the presence of a C 1 -C 4 alkane carboxylic acid and water.
2. A process according to claim 1 wherein R 1 represents H.
3. A process according to claim 1 wherein R 2 represents H, CH 3 , or CH 2 CH 3 .
4. A process according to claim 1 wherein R 3 is CH 3 or CH 2 CH 3 .
5. A process according to claim 1 wherein R 4 is H.
6. A process according to claim 1 wherein R 5 is CH 3 .
7. A process according to claim 1 wherein said process is conducted with an organic co-solvent.
8. A process according to claim 1 wherein approximately equimolar quantities of α,β-unsaturated carbonyl and sodium or potassium thiolate are employed in said process.
9. A process according to claim 8 wherein a 1-50 percent stoichiometric excess of sodium or potassium thiolate is employed in said process.
10. A process according to claim 8 wherein a 2-30 percent stoichiometric excess of sodium or potassium thiolate is employed in said process.
11. A process according to claim 8 wherein a 3-20 percent stoichiometric excess of sodium or potassium thiolate is employed in said process.
12. A process according to claim 1 wherein said alkane carboxylic acid is present in an amount equal to about 1 to 10 equivalents with respect to the α,β-unsaturated carbonyl or the sodium or potassium thiolate.
13. A process according to claim 1 wherein said alkane carboxylic acid is present in an amount equal to about 1.0 to 1.7 equivalents with respect to the α,β-unsaturated carbonyl or the sodium or potassium thiolate.
14. A process according to claim 1 wherein said alkane carboxylic acid is present in an amount equal to about 1.1 to 1.6 equivalents with respect to the α,β-unsaturated carbonyl or the sodium or potassium thiolate.
15. A process according to claim 1 wherein said process is conducted at a temperature from about 0° C. to about 70° C.
16. A process according to claim 1 wherein said process is conducted at a temperature from about 5° C. to about 60° C.
17. A process according to claim 1 wherein said process is conducted under a substantially oxygen-free atmosphere.
18. A process according to claim 17 wherein said process is conducted under nitrogen.
19. A process according to claim 1 wherein said α,β-unsaturated carbonyl and the alkane carboxylic acid are mixed together and chilled to about 0 to about 5° C. then an aqueous solution of sodium or potassium thiolate is added.
20. A process according to claim 1 wherein:
R 1 is H;
R 2 is H, CH 3 , or CH 2 CH 3 ;
R 3 is CH 3 or CH 2 CH 3 ;
R 4 is H;
R 5 is CH 3 ;
a 3-20 percent stoichiometric excess of sodium or potassium thiolate is employed in said process;
said alkane carboxylic acid is present in an amount equal to about 1.1 to 1.6 equivalents with respect to the α,β-unsaturated carbonyl or the sodium or potassium thiolate; and
said process is conducted at a temperature from about 5° C. to about 60° C.