Potassium Hydroxide → 2-(2-Tritylaminothiazol-4-yl)-2-[(2-t-butoxycarbonylprop-2-yl)-oxyimino]-acetic acid

Participants

Reaction Steps

A mixture of 1.2 g of the product of Step A, 2 ml of methanolic 1N potassium hydroxide solution and 4 ml of methanol was refluxed for 2 hours and was then cooled during which 390 mg of the starting material crystallized which meant 810 mg of the starting product was saponified. The mixture was filtered and the filtrate was evaporated to dryness. The residue was taken up in 1 ml of dimethylformamide and 2 ml of N hydrochloric acid solution (pH=2). The mixture was stirred and 10 ml of water were added thereto. The mixture was extracted with methylene chloride and the organic phase was washed with water. The wash waters were extracted with methylene chloride and the combined organic phases were dried and vacuum filtered. The filtrate was evaporated and the oil residue was taken up in 4 ml of chloroform. The solution was diluted with 30 ml of ether and crystallization was effected. After 30 minutes with stirring, the mixture was vacuum filtered and the product was rinsed with ether and dried to obtain 472 mg of the syn isomer of 2-(2-tritylamino-4-thiazolyl)-2-(1-tert.-butoxycarbonyl-1-methylethyloxyimino)-acetic acid melting at 190° C.

Provenance & Evidence