2-acetoxy-6-(tert-butyldimethylsiloxy)-10,11-(di-tert-butylsilylenedioxy)-12,12-(2',2'-dimethylpropane-1',3'-diyldioxy)-3-((4'-methoxyphenyl)thio)-1,4,4a(R*),5,5a(S*),6(S*),11(R*),11a(R*),12,12a(S*)-decahydronaphthacene