(-)-12-OXO-CALANOLIDE 2H,6H,10H-Benzo[1,2-b:3,4-b':5,6-b'']tripyran-2-one,11,12-dihydro-12-oxo-6,6,10,11-tetramethyl-4-n-propyl-,(10R,11S)- AIDS-185476 AIDS185476