Pyrrole derivatives, properties

A,B-Diheteropentalenes have only limited solubility in water. The hydrogen donor properties of the NH site of pyrrole and the hydrogen acceptor property of the oxygen atom of the furan ring can increase the solubility of the compounds containing these heteroatoms relative to the systems with only sulfur or selenium atoms in their structure. Alkylation at the nitrogen of furo[3,2-6]pyrrole derivatives increases the solubility in ethanol and other organic solvents. 

The reactions of 2-amino-2-deoxyaldoses and 1-amino-l-deoxyketoses, and their A-alkyl and A -aryl derivatives, with /3-dicarbonyl compounds give pyrrole derivatives whose nature depends somewhat upon the experimental conditions used. Accounts of these reactions, and discussions of the structures and properties of the products, are given in this Section. The mechanisms are dealt with in Section IV. 

In connection with the toxicity of the pyrrolizidine alkaloids the toxic effects of the alkaloids themselves have been reproduced by dosing experimental animals with synthetic compounds. Because the most toxic alkaloids are esters which are resistant to enzymic hydrolysis, and which are converted in vivo into pyrrole derivatives, it was expected that simpler pyrroline esters would prove to exhibit the same toxic properties as the alkaloids. This expectation was realised when it was shown that the dicarbamate (59) is rather more toxic than monocrotaline, and further that the tissue damage produced is histologically similar to that observed in cases of pyrrolizidine alkaloid poisoning. A compound of slightly lesser toxicity is the retronecine derivative (60). 

Yagupolskii, L.M. Sokolenko, T.M. Petko, K.I. Chemical properties of A-polyfluor-oethylimidazole and -pyrrole derivatives. Russ. Chem. Bull, Int. Ed. 2005, 54, 796-802. 

M. A. Vorotyntsev, M. Casalta, E. Pousson, L. Roullier, G. Boni and C. Moise, Redox properties of titanocene-pyrrole derivative and its electropolymerization, Electrochim. Acta 46, 4017-4033 (2001). 

Pyrrole derivatives bearing bile acid moieties have been synthesized and elec-trochemically polymerized. The electrochemical properties and stability of the polymer film are found to depend strongly on the length of the alkyl spacer in the monomer [225]. 

Many methine cationic dyes, styrylic (141), pyrrolic. or amino-substituted (142) derivatives of thiazolium, possess interesting anthelmintic properties (143). This last class has been used as accelerators of the catabolism and activators of cellular exchanges (144). 

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