(11aS)-3 – 7-Bis[3 – 5-bis(tert-butyl)-4-methoxyphenyl]-10 – 11 – 12 – 13-tetrahydro-5-hydroxy-5-oxide-diindeno[7 – 1-de:1′ – 7′-fg][1 – 3 – 2]dioxaphosphocin