Novel pyrazolo[1,5-a]pyridines as PI3K inhibitors: variation of the central linker group

As part of our investigation into the pyrazolo[1,5-a] pyridines as novel PI3K inhibitors, we report a range of analogues where the central linker portion of the molecule was varied while retaining the pyrazolo[1,5-a] pyridine and arylsulfonyl or arylcarbonyl groups. Isostere generating software BROOD was used to assist with producing ideas. The isoform selectivity of the compounds varied from pan-PI3K for compound 41 to p110 alpha-selective for compound 58 or p110 delta-selective for compound 57. The latter two compounds varied only in their sulphur oxidation state.