Addition of sulfur compounds to C-N multiple bonds

A solution of this salt (2.6 g) in water (10 ml) is treated with concentrated hydrochloric acid (20 ml) and then gradually with zinc dust (5 g). The temperature is kept at 40-50° until gas evolution ceases then extraction with ether and working up gives mercaptohydroquinone as long needles, m.p. 118°. 

The C-N double bond of Schiff bases reacts with mercaptoacetic esters to give, first a new C-S bond and then ring closure to 2,3-disubstituted 4-thi-azolidones 72 

Addition of thiols to A-benzylideneanthranilic acid has been described by Stacy and Morath.73 

According to Asinger and his co-workers, addition of a-mercapto ketones to aldimines affords 4-thiazolines.74 

4-Thiazolines 58 One mole each of an aldimine and 2-mercapto-3-pentanone are boiled in benzene (300 ml) under a Dean and Stark apparatus until no more water appears in the separator. Then the solvent is evaporated and the residue is distilled in a vacuum or recrystallized. The 4-thiazolines recorded in the Table below were prepared by this method. 

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