Synthesis of a cyclic urea as a nonnatural biopolymer scaffold

Article abstract of DOI:10.1016/0040-4039(96)01101-X

A cyclic urea trimer was synthesized from readily available amino acid derivatives using a simple, iterative approach. A selective amide reduction using borane (BH₃-THF) and a triphosgene-mediated cyclization are the key features in a synthesis of the cyclic urea trimer 2.