Hydrogen Bromide → HCID 178460861, compound

Participants

Reaction Conditions

Reaction Steps

The (+)-α-methylbenzylamine salt of (-)-(1-benzyloxycarbonylamino-2-mercapto-2-methylpropyl)phosphinic acid [paragraph (c)] was suspended in water, the suspension was acidified to pH 1 with 2N hydrochloric acid and extracted with two 25 ml portions of diethyl ether. The combined ethereal extracts were dried over magnesium sulphate. Removal of the solvent by evaporation gave an oil which was dissolved in 2 ml of glacial acetic acid and treated with 5 ml of 45% hydrogen bromide in acetic acid. The solution was stored at room temperature overnight. 200 ml of diethyl ether were added and the cloudy suspension was cooled at 0° C. for 2 hours. The ethereal layer was decanted off and the residue was dissolved in 15 ml of methanol. 10 ml of acetone were then added. The solution was heated under reflux for 1 hour, cooled and filtered. The filtrate was adjusted to pH 5 by adding propylene oxide. The acetone adduct crystallized out at 0° C. and was collected. The acetone adduct, which melted at 183°-185° C., was dissolved in 5 ml of boiling water, filtered and concentrated to 3 ml by boiling off excess water. 15 ml of isopropanol were added and the mixture was allowed to cool slowly to room temperature. The mixture was then cooled at 0° C. for 16 hours. The resulting crystalline solid was collected and dried, there being obtained (-)-(1-amino-2-mercapto-2-methylpropyl)phosphinic acid of melting point 211°-212° C. (decomposition; [α]D25 =-4.5° (c=1.5% in water).

Provenance & Evidence