Methyl p-toluenesulfonate → 5-Benzothiazolol,2-(methylthio)-(9CI)

To a 250 mL flask was added 2-mercapto-5-methoxybenzothiazole (5.1 g, 26 mmol), MeCN (63 mL), methyl p-toluenesulfonate (4.8 g, 26 mmol) and TEA (4.4 mL, 31 mmol). After stirring 16 h at ambient temperature, the solution was concentrated under reduced pressure. The crude material was diluted with EtOAc (200 mL), washed with water (2×75 mL), dried over Na2SO4, filtered, and concentrated. The resulting viscous oil was dissolved in DCM (40 mL), and transferred to an argon-purged 250 mL flask. The solution was cooled to −78° C. prior to the addition of a 1.0 M BBr3 solution in DCM (64 mL). The reaction suspension was allowed to warm to room temperature. After 16 h the reaction solution was cooled to −78° C. and quenched by addition of MeOH (100 mL). The resulting precipitates were isolated by vacuum filtration to yield 5-hydroxy-2-methylthio-benzothiazole (3.9 g, 76%) as a white solid.

1. concentrationthe solution was concentrated under reduced pressure
2. additionThe crude material was diluted with EtOAc (200 mL)
3. washwashed with water (2×75 mL)
4. dry with materialdried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated
7. dissolutionThe resulting viscous oil was dissolved in DCM (40 mL)
8. custompurged 250 mL flask
9. temperatureThe solution was cooled to −78° C.
10. additionto the addition of a 1.0 M BBr3 solution in DCM (64 mL)
11. temperatureto warm to room temperature
12. temperatureAfter 16 h the reaction solution was cooled to −78° C.
13. customquenched by addition of MeOH (100 mL)
14. customThe resulting precipitates
15. customwere isolated by vacuum filtration

ORD record

ord-9abaca782c9f40d8916695bde0225632

Source dataset

uspto-grants-2006_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07115640B2