1,2,3,9b-Tetrahydro-5H-imidazo[2,1-a]isoindol-5-ones as a new class of respiratory syncytial virus (RSV) fusion inhibitors. Part 2: identification of BTA9881 as a preclinical candidate.
Bond S, Draffan AG, Fenner JE, Lambert J, Lim CY, Lin B, Luttick A, Mitchell JP, Morton CJ, Nearn RH, Sanford V, Anderson KH, Mayes PA, Tucker SP.
Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in infants, young children and adults. 1,2,3,9b-Tetrahydro-5H-imidazo[2,1-a]isoindol-5-ones with general structure 1 were previously identified as promising inhibitors of RSV targeting the fusion glycoprotein. In particular, the introduction of a nitrogen at the 8-position of the tricyclic core yielded lead compounds 2 and 3. Extensive exploration of the R(2) group established that certain heterocyclic amides conferred potent RSV A&B activity and a good balance of physicochemical and pharmacokinetic properties. The antiviral activity was found to reside in a single enantiomer and compound 33a, (9bS)-9b-(4-chlorophenyl)-1-(pyridin-3-ylcarbonyl)-1,2,3,9b-tetrahydro-5H-imidazo[1',2':1,2]pyrrolo[3,4-c]pyridin-5-one (known as BTA9881), was identified as a candidate for preclinical development.