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Cuprate-Mediated Synthesis and Biological Evaluation of Cyclopropyl- and tert-Butylfarnesyl Diphosphate Analogs

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journal contribution
posted on 15.11.1996, 00:00 by YongQi Mu, Richard A. Gibbs, Lisa M. Eubanks, C. Dale Poulter
The novel farnesyl diphosphate (FPP) analog 3-cyclopropyl-3-desmethylfarnesyl diphosphate (3-cpFPP, 1) was designed as a potential mechanism-based inhibitor of the FPP-utilizing enzyme protein−farnesyl transferase (PFTase). The key step in the synthesis of 1 involved the stereoselective coupling of vinyl triflate 8 with a lower order cyclopropyl cyanocuprate to afford the desired cyclopropyl ester 13. The sterically encumbered analog 3-desmethyl-3-tert-butylfarnesyl diphosphate (3-tbFPP, 7) was synthesized via a similar route. The use of the more reactive higher order tert-butyl cyanocuprate led to lower yields of ester 11, the key intermediate in the synthesis of 7. Biological evaluation of 3-cpFPP demonstrates that it is not a time-dependent inhibitor of recombinant yeast PFTase. Instead, 3-cpFPP is an alternative substrate for this enzyme that exhibits a Km comparable to FPP and a kcat only 5-fold lower than the natural substrate. In contrast, 3-tbFPP is an exceptionally poor substrate for yeast PFTase and acts as an inhibitor of this enzyme.