A Facile and Efficient Multi‐Gram Synthesis of N‐Protected 5‐(Guanidinocarbonyl)‐1H‐pyrrole‐2‐carboxylic Acids

The synthesis of two versatile building blocks for supramolecular anion binding motifs, 5‐(N‐Boc‐guanidinocarbonyl)‐1H‐pyrrole‐2‐carboxylic acid (1) and 5‐(N‐Cbz‐guanidinocarbonyl)‐1H‐pyrrole‐2‐carboxylic acid (2) is reported. Using these building blocks, a guanidiniocarbonyl‐pyrrole anion binding site can easily be introduced into more complex molecules by using standard amide coupling conditions. Both syntheses can be performed on a multi‐gram scale. The products are obtained in pure form and can be stored as solids without decomposition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)