On the Synthesis of 3‐Amino‐pyrroles by Thorpe‐Ziegler‐Cyclization
N‐Aryl and alkylaminomethylene cyanacetic acid derivatives 1 react with α‐halogencarbonyl compounds 2 in the presence of potassium carbonate/sodium ethoxide to yield the substituted 3‐amino‐pyrroles 6. Using the same principle of cyclization pyrrole derivatives 6 can also be obtained by reaction of β‐chloro‐ and β‐alkoxymethylenemalononitriles 4 with β‐aminocarbonyl compounds 5. From the malononitrile derivatives 1 containing the methylthio group in the β‐position, and α‐halogen ketones 7, the 2‐dicyanomethylene oxazolines 8 arise which undergo alkoholysis by treatment with sodium alkoxide to form the 3‐amino‐5‐alkoxy‐pyrrole derivatives 9.
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