AIDS-109543 AIDS109543 Diethyl 1,5-dibenzyl-1,5,8,8b.beta.-tetrahydro-4a.beta.,8a.beta.-dihydroxymethyl-4,8-diphenylcyclobuta[1,2b:3,4b']dipyridine-3,7(4H, 4b.beta.H)dicarboxylate H 19 H19