Furo[3',2':3,4]naphtho[1,8-de][1,3]dioxin-9(1H)-one,2-(acetyloxy)decahydro-5-methoxy-5,10c-dimethyl-1,8-bis(methylene)-, [2R-(2a,3ab,5b,6ab,7aa,10ab,10ba,10cb)]-