A diastereoselective synthesis of the tetrahydropyridazinone core of 2-oxo-1,6-diazobicyclo[4.3.0]nonane-9-carboxylate-based peptidomimetics starting from (S)-phenylalanine

A diastereoseletvive synthesis of a peptidic tetrahydropyridazinone 10 from (S)-phenylalanine is reported. This derivative was then converted to the bicyclic peptidomimetic 11, an important class of β-strand mimetic.