Enantioselective Formal C(sp3 )-H Bond Activation in the Synthesis of Bioactive Spiropyrazolone Derivatives
Houhua Li1, Rajesh Gontla1, Jana Flegel1,2
1Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Otto-Hahn-Straße 11, 44227, Dortmund, Germany.
Abstract:
Herein, we report the first enantioselective annulation of α-arylidene pyrazolones through a formal C(sp3 )-H activation under mild conditions enabled by highly variable RhIII -Cpx catalysts. The method has a wide substrate scope and proceeds with good to excellent yields and enantioselectivities. Its synthetic utility was demonstrated by the late-stage functionalization of drugs and natural products as well as the preparation of enantioenriched [3]dendralenes. Preliminary biological investigations also identified the spiropyrazolones as a novel class of Hedgehog pathway inhibitors.
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