(1′R,2R,4S,5R,8′S,10′R)-1′,8′,10′-Trichloro-3′,6′-dimethoxy-3,4-dimethyl-5-phenylspiro[1,3-oxazolidine-2,9′-tricyclo[6.2.1.0~2,7~]undeca[2,4,6]triene]