ABSTRACT
We describe a catalytic cascade sequence involving directed C(sp3 )-H activation followed by ß-heteroatom elimination to generate a PdII (π-alkene) intermediate that then undergoes redox-neutral annulation with an ambiphilic aryl halide to access 5- and 6-membered (hetero)cycles. Various alkyl C(sp3 )-oxygen, nitrogen, and sulfur bonds can be selectively activated, and the annulation proceeds with high diastereoselectivity. The method enables modification of amino acids with good retention of enantiomeric excess, as well as σ-bond ring-opening/ring-closing transfiguration of low-strain heterocycles. Despite its mechanistic complexity, the method employs simple conditions and is operationally straightforward to perform.
ABSTRACT
Poly-ADP-ribose-polymerase (PARP) inhibitors have achieved regulatory approval in oncology for homologous recombination repair deficient tumors including BRCA mutation. However, some have failed in combination with first-line chemotherapies, usually due to overlapping hematological toxicities. Currently approved PARP inhibitors lack selectivity for PARP1 over PARP2 and some other 16 PARP family members, and we hypothesized that this could contribute to toxicity. Recent literature has demonstrated that PARP1 inhibition and PARP1-DNA trapping are key for driving efficacy in a BRCA mutant background. Herein, we describe the structure- and property-based design of 25 (AZD5305), a potent and selective PARP1 inhibitor and PARP1-DNA trapper with excellent in vivo efficacy in a BRCA mutant HBCx-17 PDX model. Compound 25 is highly selective for PARP1 over other PARP family members, with good secondary pharmacology and physicochemical properties and excellent pharmacokinetics in preclinical species, with reduced effects on human bone marrow progenitor cells in vitro.
