Hydrochloric Acid → 6-Methoxybenzothiazole

2-Amino-6-methoxybenzothiazole (9.0 g) in dry DMF (10 ml) was added dropwise over 35 minutes to a stirred solution of t-butyl nitrite (9.9 ml) in DMF (40 ml) at 65° C. The temperature of the mixture was kept <73° C. during the addition. On complete addition of the solution of benzothiazole, the dark red solution was stirred for an additional 15 minutes, cooled to ambient temperature then poured into dilute hydrochloric acid (200 ml) and diluted with brine. The dark red suspension was extracted with diethyl ether and the solid filtered then washed with further water and diethyl ether. The diethyl ether extracts were combined and the aqueous fraction re-extracted with ethyl acetate. The organic fractions were combined, washed with water and dried over magnesium sulphate then evaporated to give a brown solid. The solid was purified by flash column chromatography on silica gel (40-60 mesh) eluting with hexane/ethyl acetate (4:1 by volume) to give 6-methoxybenzothiazole as a colourless solid (2.1 g).

1. additionThe temperature of the mixture was kept <73° C. during the addition
2. extractionThe dark red suspension was extracted with diethyl ether
3. filtrationthe solid filtered
4. washthen washed with further water and diethyl ether
5. extractionthe aqueous fraction re-extracted with ethyl acetate
6. washwashed with water
7. dry with materialdried over magnesium sulphate
8. customthen evaporated
9. customto give a brown solid
10. customThe solid was purified by flash column chromatography on silica gel (40-60 mesh)
11. washeluting with hexane/ethyl acetate (4:1 by volume)

ORD record

ord-e643c78613d24342b71b03095488ad58

Source dataset

uspto-grants-2011_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07956188B2