Triethylamine → 7-hydroxymethyl-2-methylthio-4-oxo-4H-1-benzothiopyran

Temperature

-10 °C

7-Carboxy-2-methylthio-4-oxo-4H-1-benzothiopyran (1.48 g, 5.87 mmol) was suspended in tetrahydrofuran (30 ml), added with triethylamine (1 ml, 7.17 mmol) and cooled to −10° C. Then, the reaction mixture was added dropwise with ethyl chlorocarbonate (0.6 ml, 5.94 mmol) and stirred at 0-5° C. for 0.5 hour. The reaction mixture was filtered and the insoluble matter was further washed with tetrahydrofuran (10 ml×2 times). The washing liquid was mixed with the previous tetrahydrofuran solution. Sodium borohidride (568 mg, 15 mmol) was suspended in water (8 ml) and added dropwise with the previously obtained tetrahydrofuran solution over 45 minutes under ice-water cooling. The reaction mixture was acidified with 2N hydrochloric acid and extracted by ethyl acetate (300 ml), washed with saturated saline solution and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure and the residue was washed with ether to obtain 800mg (yield: 57%) of substaintially pure 7-hydroxymethyl-2-methylthio-4-oxo-4H-1-benzothiopyran.

1. filtrationThe reaction mixture was filtered
2. washthe insoluble matter was further washed with tetrahydrofuran (10 ml×2 times)
3. additionThe washing liquid was mixed with the previous tetrahydrofuran solution
4. additionadded dropwise with the previously obtained tetrahydrofuran solution over 45 minutes under ice-water cooling
5. extractionextracted by ethyl acetate (300 ml)
6. washwashed with saturated saline solution
7. dry with materialdried over anhydrous magnesium sulfate
8. customThe solvent was removed under reduced pressure
9. washthe residue was washed with ether

ORD record

ord-189e5933d9af4e3bb4c913a5c3fc978f

Source dataset

uspto-grants-2001_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06294527B1