Reaction #3042

Reaction equation

tri-n-butyl tin hydride

AIBN

AIBN

5-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methylene]-3-(ethylmethylamino)-2-thioxo-4-thiazolidinone

hydrochloric acid

→

desired product

Yield 29.8%

5-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methylene]-3-(ethylmethylamino)-4-thiazolidinone

Yield 29.8%

Solvents

hexane

chloroform

toluene

ethyl acetate

Conditions

Workup

1. 1
   Temperatureto reflux temperature for 30 minutes
2. 2
   Temperatureat reflux temperature for an additional 30 minutes
3. 3
   Temperaturecooled
4. 4
   Othertransferred to a separatory funnel
5. 5
   Otherseparated
6. 6
   WashThe organic layer was washed with brine
7. 7
   Dryingdried over sodium sulfate
8. 8
   Filtrationfiltered
9. 9
   Otherevaporated
10. 10
    Otherto give an orange/red oil which
11. 11
    Filtrationfiltered
12. 12
    OtherThe filtrate was chromatographed on a silica gel column
13. 13
    workup.ADDITIONas containing product
14. 14
    Otherwere evaporated
15. 15
    workup.ADDITIONTo these fractions were added 15 ml of hexane
16. 16
    Temperaturethe resultant solution was heated slightly
17. 17
    OtherA precipitate formed which
18. 18
    OtherThe resultant mixture was triturated for about 2 hours
19. 19
    Filtrationfiltered
20. 20
    Washwashed with hexane

Procedure

7.02 g of 5-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methylene]-3-(ethylmethylamino)-2-thioxo-4-thiazolidinone (from Example 40D) and 86.3 ml of toluene were stirred and heated to 60° C. under a nitrogen atmosphere. To this was added 18.6 ml of tri-n-butyl tin hydride and 0.43 g of AIBN. The resultant mixture was heated to reflux temperature for 30 minutes. At that time an additional 0.43 g of AIBN was added. The resultant mixture was heated at reflux temperature for an additional 30 minutes, cooled and transferred to a separatory funnel. To this was added 100 ml of 1N hydrochloric acid and 100 ml of ethyl acetate. The resultant mixture was shaken and separated. The organic layer was washed with brine, dried over sodium sulfate, filtered, evaporated and subsequently chased with chloroform to give an orange/red oil which was taken up in 50 ml of chloroform and filtered. The filtrate was chromatographed on a silica gel column using an 8000 ml gradient of 10-40% ethyl acetate in hexane. Those fractions identified as containing product were evaporated and chased with chloroform. To these fractions were added 15 ml of hexane and the resultant solution was heated slightly. A precipitate formed which was diluted to about 25 ml with additional hexane. The resultant mixture was triturated for about 2 hours, filtered and then washed with hexane to yield 1.94 g of the desired product, m.p. 133.5°-135° C.

Source