Identification of 4-(4-aminopiperidin-1-yl)-7H-pyrrolo[2,3-d]pyrimidines as selective inhibitors of protein kinase B through fragment elaboration.

John J Caldwell, Thomas G Davies, Alastair Donald, Tatiana McHardy, Martin G Rowlands, G Wynne Aherne, Lisa K Hunter, Kevin Taylor, Ruth Ruddle, Florence I Raynaud, Marcel Verdonk, Paul Workman, Michelle D Garrett, Ian Collins

Index: J. Med. Chem. 51 , 2147-57, (2008)

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Abstract

Fragment-based screening identified 7-azaindole as a protein kinase B inhibitor scaffold. Fragment elaboration using iterative crystallography of inhibitor-PKA-PKB chimera complexes efficiently guided improvements in the potency and selectivity of the compounds, resulting in the identification of nanomolar 6-(piperidin-1-yl)purine, 4-(piperidin-1-yl)-7-azaindole, and 4-(piperidin-1-yl)pyrrolo[2,3- d]pyrimidine inhibitors of PKBbeta with antiproliferative activity and showing pathway inhibition in cells. A divergence in the binding mode was seen between 4-aminomethylpiperidine and 4-aminopiperidine containing molecules. Selectivity for PKB vs PKA was observed with 4-aminopiperidine derivatives, and the most PKB-selective inhibitor (30-fold) showed significantly different bound conformations between PKA and PKA-PKB chimera.