Diastereoselective Synthesis of Amino Acid‐Substituted 2,2’‐Bipyrrolidines

Bipyrrolidines are important chiral diamines with application in organocatalysis and the synthesis of ligands for transition metal complexes. Conventionally, these compounds are prepared by a photochemical dimerization of pyrrole, however, the method is not stereoselective, the isolation of stereopure products is tedious, and the method is difficult to apply to substituted bipyrrolidines. In this manuscript, it is shown that α‐amino acid‐substituted bipyrrolidines can be prepared in moderate to good yields by an intramolecular diamination reaction promoted by electrophilic iodinating agents. If amino acids with a sterically‐demanding side chain such as valine or phenylalanine are used, high diastereoselectivities have been observed. The resulting N , N ’‐amino acid substituted bipyrrolidines could function after deprotection as tetradentate transition metal ligands.