Hydrochloric Acid → 6-Chloro[1,3]dioxolo[4,5-f][1,3]benzothiazole

Participants

Reaction Steps

The product from Step 1 (1.7 g) was partially dissolved in dry acetonitrile (50 cm3) and added in portions to a stirred suspension of copper(II) chloride (1.41 g) and tert-butyl nitrite (1.56 cm3) in dry acetonitrile (15 cm3) at 60° C. The mixture was heated for 1 hr., cooled to ambient temperature, poured into water/diethyl ether and acidified with aqueous 2M hydrochloric acid. The aqueous fraction was separated and extracted with diethylether (3×100 cm3) and the combined organic fractions washed with water (3×50 cm3) and dried (magnesium sulphate). The solution was evaporated under reduced pressure to give a brown solid. The solid was fractionated by absorbing it onto silica and eluting with hexane/ethyl acetate (50:1 by volume) to give the required product as a colourless solid, M+ =213; 1NMR (CDCl3): δ7.36(1H,s): 7.14(1H,s); 6.08(2H,s); mp 131°-2° C.

Provenance & Evidence