A three-component Mannich-type condensation leading to phosphinic dipeptides—extended transition state analogue inhibitors of aminopeptidases

N-Protected α-aminoalkylphosphinic acids bearing a P–H function were found to be novel practical building blocks in three-component condensations with formaldehyde and secondary amines (amino acids). Such Mannich-type N-phosphonomethylation is a common approach for phosphorus acid derived substrates and leads to multifunctional (phosphonic/amino/carboxylic) compounds of diverse relevance. The utility of this reaction was examined for construction, in a single synthetic step, of advanced phosphinic pseudodipeptides designed to act as extended transition state analogue inhibitors of selected aminopeptidases. Phosphinomethylation of primary amino acids was less efficient and yielded mixtures of products which were separated into individual components, and their structures identified.