Hydrochloric Acid → HCID 13590117, compound

Participants

Reaction Steps

The requisite 1-chloro-6-methoxy-4-nitrothioxanthone was prepared as follows: To a prewashed (pentane) suspension of NaH in 500 ml of tetrahydrofuran cooled to 0° was added dropwise over about 25 minutes a solution of 35.4 g of 2,6dichloro-5-nitrobenzoic acid in 200 ml of tetrahydrofuran. After about five minutes a solution of 20 g of m-methoxybenzenethiol in 50 ml of tetrahydrofuran was added, and the mixture was stirred for 20 hours as it gradually came to ambient temperature. The mixture was treated with a 10% aqueous hydrochloric acid solution, extracted into ethyl acetate, dried, and the solvent was removed in vacuo. The orange gum was purified by flash chromatography on SiO2 with a 90:5:0.5 mixture of methylene chloride:methanol:acetic acid. The resulting oil was sufficiently pure for use in the next step. A solution of this material (24.8 g) in 120 ml of trifluoroacetic acid was treated with 60 ml of trifluoroacetic anhydride and allowed to stir at room temperature for 30 minutes. The solution was diluted with acetonitrile, and the precipitate was collected and triturated with boiling acetonitrile to give 15.8 g of the product, mp 254°-258°.

Provenance & Evidence