(11bR)-2 – 6-Bis(4-chlorophenyl)-8 – 9 – 10 – 11 – 12 – 13 – 14 – 15-octahydro-4-hydroxy-4-oxide-dinaphtho[2 – 1-d:1′ – 2′-f][1 – 3 – 2]dioxaphosphepin