(1'R.3'aR.8'aS.9'S.9'aS)-1'.3'a.5'.7'.8'.8'a.9'.9'a-Octahydro-1'-methyl-3'-oxo-N.N-diphenyl-spiro[1.3-dioxolane-2.6'(3'H)-naphtho[2.3-c]furan]-9'-carboxamide