(+)-12-Oxocalanolide A 183904-55-4 AIDS-033638 AIDS033638 trans-(+)-2H,6H,12H-Benzo[1,2-b:3,4-b':5,6-b'']tripyran-2,12-dione, 10,11-dihydro-6,6,10,11-tetramethyl-4-propyl-, (10R,11R)-