Ammonium Chloride → N-benzyloxycarbonyl-S-(2-aminophenyl)cysteine

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Reaction Steps

A 5 l 3-neck flask fitted with a mechanical stirrer and condenser is charged with 62.1 g of S-(o-nitrophenyl)-N-carbobenzyloxy-L-cysteine, 17.6 g of ammonium chloride and 3 l of methanol. To this mixture is added 150 g of zinc dust. The reaction is heated for 4 hr at reflux and then stirred overnight at room temperature. The reaction is filtered through celite and the solids are further washed with 300 ml of boiling methanol. The methanol fractions are combined and concentrated. The residue is dissolved in 1200 ml of 1N hydrochloric acid and filtered through celite. The acidic solution is cooled to 0° C. and the pH is adjusted to 5 with saturated sodium acetate. The resulting white precipitate is collected and dried at 80° C. in vacuo to give S-(o-aminophenyl)-N-carbobenzyloxy-L-cysteine; m.p. 161°-162° C.; [α]D =-50° ((c=1.0, absolute ethanol).

Provenance & Evidence