Orthoamide, LVIII . Kondensationsreaktionen von CH2-aciden Verbindungen mit Orthoamiden von Carbonsäuren und Alkincarbonsäuren / Orthoamides, LVIII . Condensation Reactions of CH2-Acidic Compounds with Orthoamides of Carboxylic Acids and Alkyne Carboxylic Acids

Abstract

The orthoamide derivatives 1s and 2e were prepared from the guanidinium salt 7a and the appropriate carbanions. Cleavage of the orthoamide 2e with benzoyl chloride affords the amidinium salt 10a, which can be transformed into the amidinium salt 10b by an anion exchange reaction. The enamines 11a-i, 12a-c, 13a, b, 14a-c, 15a, b, 16, 17a, b, 18a, b, 19a, b, 20 were prepared by condensation of CH2-acidic compounds with the carboxylic acid orthoamides 2a-j. The orthoamide 2d reacts with 1-nitropropane to give the amidinium salt 27a which is transformed into the salt 27b. From benzyl cyanide and orthoamides 2g, i the enamines 30 and 32 were obtained. Similar condensation reactions were performed with the orthoamides of alkyne carboxylic acids 1b, 1c, 1d, 1e, 1p, 1s, giving the push-pull-butadiene derivatives 35a-f, 36a-f, 37a-j, 38a, b, 39a, b, 40a, b. Crystal structure analyses of the butadiene derivatives 37a, 39a, b, 40a, b and 42 were performed, showing that in 37a, 39b, 40a, b by far the shortest bond distance is between C-2 and C-3 of the butadiene system. In 39a the bonds between C1-C2, C2-C3 and C3-C4 are nearly of equal length, whereas in the 1,3-diene unit of 42 the shortest bonds are between C1-C2 and C3-C4.