(11BS)-2,6-bis(3,5-di-tert-butylphenyl)-4-hydroxydinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepine 4-oxide

(11BS)-2,6-bis(3,5-di-tert-butylphenyl)-4-hydroxydinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepine 4-oxide