Carbon Dioxide → Imidazo[5,1-B]thiazole-7-carboxylic acid

Participants

Reaction Steps

A 0.95 M ethylmagnesium bromide/THF solution (12.6 ml) was added dropwise to a solution (50 ml) of 2.501 g of 7-iodoimidazo[5,1-b]thiazole in THF ac −70° C. The mixture was stirred for 30 min. Carbon dioxide (which had been evolved from about 5 g of dry ice and passed through a calcium chloride tube) was introduced into the reaction solution at the same temperature over a period of 40 min. The reaction solution was allowed to stand at −20° C. overnight, and then added to an ice cold mixed solution composed of an aqueous sodium hydroxide (0.41 g) solution (100 ml) and ether (200 ml) with stirring. The mixture was stirred for one hr. The organic layer was separated and concentrated under the reduced pressure by a minor amount, and the remaining organic solvent was removed by distillation. The residue was adjusted to pH 3.5 by the addition of 2 N hydrochloric acid under ice cooling. The resultant precipitate was washed with a minor amount of cold water, and then dried under the reduced pressure to give 1.407 g of imidazo[5,1-b]thiazole-7-carboxylic acid.

Provenance & Evidence