(9'R-(9' alpha(4S*(R*)),9'a beta))-4-(2-(1-(acetyloxy)-2-methylpropyl)-4-oxo-3(4H)-quinazolinyl)-1',3,4,9'a-tetrahydro-1'-hydroxy-2',2'-dimethylspiro(furan-2(5H),9'-(9H)imidazo(1,2-a) indole)-3',5(2'H)-dione