This specialty chemical is a chiral phosphorus ligand with a unique (11aS)-configured diindeno[7,1-de:1',7'-fg][1,3,2]dioxaphosphocin core, featuring 3,5-dimethylphenyl substituents at positions 3 and 7, a 5-oxide, and 5-hydroxy group. It is primarily used in asymmetric catalysis as a ligand for copper-catalyzed enantioselective conjugate additions of organozinc reagents to α,β-unsaturated carbonyls and other Michael acceptors, delivering high enantioselectivities. This niche application supports the synthesis of chiral intermediates for pharmaceuticals and fine chemicals.