Orthoamide. LI. Push‐Pull‐Butadiene und Heterocyclen aus CH2‐aciden Verbindungen und Orthoamiden von Alkincarbonsäuren

Orthoamides. LI. Push-Pull-Butadienes and Heterocycles from Alkyne Carboxylic Acid Orthoamides and CH2-acidic Compounds The acetylides 4b, 4f react with N,N,N′,N′,N″,N″-hexamethylguanidiniumchloride (5) to give the orthoamides 6b, 6f, resp. From CH2-acidic compounds and the orthoamides 6a, c, e can be obtained the push-pull-substituted butadienes 8a–8aj. The 2,3,5-trimethyl-thiadiazolium salt 9 does not condense with 6e, as other CH2-acidic compounds do, instead the vinylogous guanidinium salt 10a is produced. On heating, the ketenaminals 8d, aa cyclize to give the pyridone-carbonitriles 11a, b, resp. From 4-amino-coumarins 12 and the orthocarboxylic acid amideacetals 13a, b and the ketenaminal 16 resp., the amidines 14a–c and the heterocyclic compounds 15a–c resp., are formed. The enamines 17a–c, 19a, b react with the orthoamides 6a–f to give the pyridine derivatives 18a–1, 20a–h and 21a, b, resp. Analogously, from 6-aminouracil 22 and 6a, b, e, f are formed the pure 7-dimethylaminopyrido[2,3-d] pyrimidines 23a, b or mixtures of compounds 23c, d and the isomeric 4-dimethylamino-pyrido[2,3-d]pyrimidines 24a, b resp., which can be separated via their salts 25a,b/26a,b. The heterocyclic compounds 30a–d, 32a,b can be prepared from the pyrazole derivatives 28, 31 resp. and the orthoamides 6a–f.