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 p110α-selective for ...