Orthoamide und Iminiumsalze, XCVa. Umsetzungen von Orthoamiden von Alkin-Carbonsäuren mit Acetophenonen und Acetophenon-Phenylhydrazonen.

The orthoamides of alkyne carboxylic acids 4 react with acetophenones 5 – catalyzed by trialkylborates – to give ketene aminals 6, which can be transformed to 5-amino-5-hydrazino-penta-2,4-dien-1-ones 10 by treatment with 2,4-dinitro-phenylhydrazine. From acetophenone-phenylhydrazones 12 and orthoamides 4 1H-1,2-diazepines 18 (fett) are formed at room temperature, whereas 4-dimethylamino-pyridines 22 are obtained at elevated temperatures. The diazepine 18a is degraded to the pyridine-derivative 22b upon heating. The N-unsubstituted acetophenone-hydrazone 25 reacts with 4c to give amidrazone 26. The constitution of compounds 18a, 22a, 22b, 26 is established by crystal structure analyses. [ABSTRACT FROM AUTHOR]