The synthesis of polisubstituted thienylpyrroles and the study of their activity as plant growth stimulators

Aim. To develop the optimal method for the synthesis of new polysubstituted thienylpyrroles and study them as cereal growth stimulants. Results and discussion. Preparative methods for the synthesis of 4-(5-carboxythiophen-2-yl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid, 5-(5-carboxythiophen-2-yl)-2,4-dimethyl-1H-pyrrol-3-carboxylic acid and ethyl 4-(4-amino-5)-thoxycarbonyl (thiophen-2-yl)-3,5-dimethyl-1H-pyrrole-2-carboxylate have been developed by step reactions. 4-(5-Carboxythiophen-2-yl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid is the most promising for the study of the growth-stimulating activity on grain seeds. Experimental part. Using ethyl 4-acyl-3,5-dimethyl-1H-pyrrole-2-carboxylate and ethyl 5-acetyl-2,4-dimethyl- 1H-pyrrole-3-carboxylate as starting compounds 4-(5-carboxythiophen-2-yl)-3,5-dimethyl-1H-pyrrole-2-carboxylic and 5-(5-carboxythiophen-2-yl) 2,4-dimethyl-1H-pyrrol-3-carboxylic acid were obtained. By the action of the Wilsmeier-Haack reagent on the latter the corresponding pyrroles with the chlorvinylcarbaldehyde fragment were isolated; their post-cyclization with ethyl ester of thioglycolic acid and the subsequent hydrolysis leads to the formation of thienylpyroldicarboxylic acids. The study of the physiological activity of the compounds synthesized was performed on seeds of different varieties of wheat and barley. Conclusions. By means of sequential reactions the polysubstituted thienylpyrrolcarboxylic acids previously unknown and their esters have been synthesized. The features of the study of these compounds as plant growth stimulants have been revealed.