Discovery of a novel class of BK channel openers: Enantiospecific synthesis and BK channel opening activity of 3-(5-chloro-2-hydroxyphenyl)-1,3-dihydro-3-hydroxy-6-(trifluoromethyl)-2H-indol-2-one

3-Aryl-3-hydroxyindol-2-ones have been identified as a novel class of BK channel openers. Synthesis of both racemic and chiral 3-aryl-3-hydroxyindolones is described along with their electrophysiological evaluation as activators of the cloned BK channel mSlo expressed in Xenopus laevis oocytes. The preliminary SAR data indicate the importance of both an electron-withdrawing substituent on the oxindole nucleus and the phenolic hydroxyl for expression of BK channel opening properties. Moreover, the dependence of BK channel opening activity on the absolute configuration of the chiral center in this pharmacophore has been demonstrated. (C) 1997 Elsevier Science Ltd.