AIDS-109540 AIDS109540 Dimethyl 1,5,8,8b.beta.-tetrahydro-4a.beta.,8a.beta.-dihydroxymethyl-1,5-dimethyl-4,8-bis(4-methoxyphenyl)cyclobuta[1,2b:3,4b']dipyridine-3,7(4H, 4b.beta.H)dicarboxylate