The development of effective respiratory syncytial virus (RSV) fusion glycoprotein (F protein) inhibitors against both wild-type and the D486N-mutant F protein is urgently required. We recently reported a 15-membered macrocyclic pyrazolo[1,5-a]pyrimidine derivative 4 that exhibited potent anti-RSV activities against not only wild-type, but also D486N-mutant F protein. However, NMR studies revealed that the 15-membered derivative 4 existed as a mixture of atropisomers. An optimization study of the linker moiety between the 2-position of the benzoyl moiety and the 7-position of the pyrazolo[1,5-a]pyrimidine scaffold identified a 16-membered derivative 42c with an amide linker that showed a rapid interconversion of atropisomers. Subsequent optimization of the 5-position of the pyrazolo[1,5-a]pyrimidine scaffold and the 5-position of the benzoyl moiety resulted in the discovery of a potent clinical candidate 60b for the treatment of RSV infections.

迫切需要开发针对野生型和D486N突变型F蛋白的有效呼吸道合胞病毒（RSV）融合糖蛋白（F蛋白）抑制剂。我们最近报道了一个15元的大环吡唑并[1,5- a ]嘧啶衍生物4，它不仅针对野生型，而且针对D486N突变F蛋白均表现出强大的抗RSV活性。但是，NMR研究表明15元衍生物4以阻转异构体的混合物形式存在。对苯甲酰基部分的2-位和吡唑并[1,5- a ]嘧啶支架的7位之间的连接子部分的优化研究确定了16元衍生物42c酰胺接头显示出快速阻转异构体。吡唑并[1，5- a ]嘧啶支架的5-位和苯甲酰基部分的5-位的随后优化导致发现了用于治疗RSV感染的有效临床候选物60b。