4-Nitrobenzyl sulfide

It can also be prepared from -nitrobenzyl alcohol and sodium sulfide,4 by heating -nitrobenzaldehyde with sodium bisulfite 5 and decomposing the addition product with hydrochloric acid, or in low yield by the reduction of />-nitrobenzaldoxime with ammonium sulfide 6 7 and subsequent acid hydrolysis of the amino oxime. 

The electrophile used in thioamide alkylation must possess a sufficiently acidic a-proton for abstraction in the following step to initiate sulfur extrusion. Common electrophiles include a-activated carbonyl compounds such as esters, ketones, malonates and nitriles. However, alkylation with 4-nitrobenzyl bromide (Scheme 3) provided an intermediate iminium species containing a sufficiently acidic benzylic proton to promote subsequent sulfide contraction. ... 

Protection of carboxylic acids. The p-nitrobenzyl group is not useful for protection of carboxyl groups of penicillins and cephalosporins because hydro-genolysis can present a problem with sulfur-containing substrates. Lilly chemists have found that the esters can be reduced with sodium sulfide (NaaS-OHaO) in aqueous THF, DMF, or acetone at 0° (25-35 minutes). In the case of 3-cephem esters, the reduction is accompanied by isomerization of the double bond to the A -position (last example). 

CARBOXYLIC GROUPS Chloromethyl methyl sulfide. 2-Hydroxymethyl-anthraquinone. p-Nitrobenzyl bromide. 

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