Synthesis of chiral nine and twelve-membered cyclic polyamines from natural building blocks

A rational strategy for the facile and efficient cyclization of amino acid-based linear precursors forming nine and twelve-membered cyclic peptidomimetics is reported. The resulting chiral lactams can readily be reduced to substituted cyclic polyamine analogues of 1,4,7,10-tetraaza-cyclododecane (cyclen) and 1,4,7-triaza-cyclononane (TACN)