Aus dem Thiosemicarbazid (I) werden mit aromatischen Aldehyden (II) die Thiosernicarbazone (III) hergestellt, die nach Isolierung zu den Thiadiazolinen (IV) cyclisiert werden und auf antibaktenelle Wirkung geprüft werden.

Ring-Chain Tautomerim in the Acid Esters of Pyrdine-2 : 3-dimrboxylic Acid. By J. KENYON and KUMAR THAKER.Pyridine-2 : 3-dicarboxylic anhydride and methanol combine exothermally in equimolecdar proportions a t room temperature, to form a viscous compound which is probably a hemi-acetal. Within an hour a t room temperature this changes spontaneously and completely into crystalline methyl 2-carboxypyridine-3-carboxylate which in turn changes to the isomeric methyl 3-carboxypyridine-2-carboxylate when its solutions are heated ; conversely methyl 3-carboxypyridine-2-carboxylate is smoothly re-converted into methyl 2-carboxypyridine-3-carboxylate at 150'. The viscous compound is hygroscopic and forms a stable crystalline hydrate. Both the viscous compound and its crystalline hydrate with diazomethane readily give dimethyl pyridine-2 : 3-dicarboxylate.(+ )-sec.-Butyl 2-carboxypyridine-3-carboxylate, when heated in ethyl acetate, is converted into ( + ) -sec.-butyl 3-carboxypyridine-2-carboxylate without significant loss of molecular cllssymmetry. (-)-sec.-Butyl 3-carboxypyridine-2-carboxyIate is smoothly decarboxylated a t 160' to optically pure (-)-sec.-butyl nicotinate.BY heating a mixture of pyridine-2 : 3-carboxylic anhydride and methanol for several hours, Kirpal obtained a methyl carboxypyridinecarboxylate which, since it gave methyl nicotinate on decarboxylation, he believed to be methyl 2-carboxypyridine-3-carboxylate (V). Later he showed that by the successive action of ammonia, hypobromite, and heat this compound gave 2-aminopyridine; accordingly he concluded that the compound was

Das Benzoesäurehydrazid (I) liefert mit den Benzaldehyden (II) die Acylhydrazone (III), an die sich die α‐Mercaptocarbonsäuren (IV) zu den Thiazolidinonen (V) addieren.

Das Hydrazid (I) reagiert mit den Aldehyden (II) zu den Hydrazonen (IIIa), die mit Phenylisothiocyanat zu den Thioharnstoffen (IIIb) umgesetzt werden.

Die Benzaldehyde (I) kondensieren mit Isonicotinsäurehydrazid (II) zu den Aroylhydazonen (III), an die sich die α‐Mercaptocarbonsäuren (IV) unter Ringschluß zu den Thiazolidinonen (V) addieren.