text: Building on the reactivity of the triphenylphosphine ligand, the structure of ligands used for the Tsuji–Trost reaction quickly became more complex. Today, these ligands may contain phosphorus, sulfur, nitrogen or some combination of these elements, but most studies have concentrated on the mono- and diphosphine ligands. These ligands can be further classified based on the nature of their chirality, with some ligands containing central chirality on the phosphorus or carbon atoms, some containing biaryl axial chirality, and others containing planar chirality. 
  Diphosphine ligands with central chirality emerged as an effective type of ligand (particularly for asymmetric allylic alkylation procedures) with the Trost Ligand being one such example.
  Phosphinooxazolines (PHOX) ligands have been employed in the AAA, particularly with carbon-based nucleophiles.