(+/-)-10,11-trans,11,12-trans-10,11-Dihydro-10-ethyl-12-hydroxy-4-propyl- 6,6,11-trimethyl-2H,6H,12H-benzo[1,2-b:3,4-b':5,6-b'']tripyran-2-one AIDS-058239 AIDS058239 Calanolide analog