Our initial findings around aryl sulfonamide series led to N-(3, 5-dichloro-2-methoxyphenyl)- 3-(1-methylpiperidin-4-ylamino)-4-methoxy benzenesulfonamide as potent and selective 5- HT6 receptor (5-HT6R) antagonist with reasonable pharmacokinetic properties and activity in animal models of cognition. However, lack of brain penetration and P-glycoprotein liability makes this scaffold unsuitable for further development. Our goal was to identify small ...