A two stage click-based library of protein tyrosine phosphatase inhibitors Original Research Article

Protein tyrosine phosphatases (PTPs) are important regulators of signal transduction pathways. Potent and selective PTP inhibitors are useful for probing these pathways and also may serve as drugs for the treatment of a variety of diseases including type 2 diabetes and infection by the bacterium Yersinia pestis. In this report Cu(I)-catalyzed ‘click’ cycloaddition reactions between azides and alkynes were employed to generate two sequential libraries of PTP inhibitors. In the first round library methyl 4-azidobenzoylformate was reacted with 56 mono- and diynes. After hydrolysis of the methyl esters, the resulting α-ketocarboxylic acids were assayed in crude form against the Yersinia PTP and PTP1B. Four compounds were selected for further evaluation, and one compound was chosen as the lead for generation of the second round library. This lead compound was modified by conversion of an alcohol into an azide group, and the resulting azide was reacted with the same 56 mono- and diynes that were used in the first generation library. After screening the crude inhibitors against the Yersinia PTP and PTP1B, four compounds were selected and evaluated in pure form against the Yersinia PTP, PTP1B, TCPTP, LAR, and CD45. The best bis(α-ketocarboxylic acid) inhibitor 34 had an IC50 value of 550 nM against the Yersinia PTP and an IC50 value of 710 nM against TCPTP. The most potent inhibitor containing a single α-ketocarboxylic acid group 32 had IC50 values of 2.1, 5.7, and 2.6 μM against the Yersinia PTP, PTP1B, and TCPTP, respectively.