17,20-Lyase inhibitors. Part 4: Design, synthesis and structure–activity relationships of naphthylmethylimidazole derivatives as novel 17,20-lyase inhibitors

Non-steroidal CYP17A1 Inhibitors: Discovery and Assessment

CYP17A1 is an enzyme that plays a major role in steroidogenesis and is critically involved in the biosynthesis of steroid hormones. Therefore, it remains an attractive target in several serious hormone-dependent cancer diseases, such as prostate cancer and breast cancer. The medicinal chemistry community has been committed to the discovery and development of CYP17A1 inhibitors for many years, particularly for the treatment of castration-resistant prostate cancer. The current Perspective reflects upon the discovery and evaluation of non-steroidal CYP17A1 inhibitors from a medicinal chemistry angle. Emphasis is placed on the structural aspects of the target, key learnings from the presented chemotypes, and design guidelines for future inhibitors.

Solvent switchable cycloaddition: a (one-pot) metal-free approach towards N-substituted benzo[e]- or [f]isoindolones via C(sp(2))-H functionalization

The tuning of selective ring closure is a nontrivial challenge in synthetic organic chemistry. Herein we report a solvent switchable metal-free [4 + 2] cycloaddition approach via Csp(2)-H functionalization. The protocol is highly atom economical with water being the only by-product, delivering N-substituted benzo[e]- or [f]isoindolones in high yields.

Steric spacing of molecular linkers on passivated Si(111) photoelectrodes

Surfaces with high photoelectrochemical and electronic quality can be prepared by tethering small molecules to single-crystalline Si(111) surfaces using a two-step halogenation/alkylation method (by Lewis and co-workers).1-7 We report here that the surface coverage of custom-synthesized, phenyl-based molecular linkers can be controlled by varying the steric size of R-groups (R=CH3, C6H11, 2-ethylhexyl) at the periphery of the linker. Additionally, the linkers possess a para triflate group (-O2SCF3) that serves as a convenient analytical marker and as a point of covalent attachment for a redox active label. Quantitative X-ray photoelectron spectroscopy (XPS) measurements revealed that the surface coverage systematically varies according to the steric size of the linker: CH3 (6.7±0.8%), CyHex (2.9±1.2%), EtHex (2.1±0.9%). The stability of the photoelectrochemical cyclic voltammetry (PEC-CV) behavior was dependent on an additional methylation step (with CH3MgCl) to passivate residual Si(111)-Cl bonds. Subsequently, the triflate functional group was utilized to perform Pd-catalyzed Heck coupling of vinylferrocene to the surface-attached linkers. Ferrocene surface coverages measured from cyclic voltammetry on the ferrocene-functionalized surfaces Si(111)-8a/CH3-Fc (R=CH3) and Si(111)-8c/CH3-Fc (R=2-EtHex) are consistent with the corresponding Fe 2p XPS coverages and suggest a ∼1:1 conversion of surface triflate groups to vinyl-Fc sites. The surface defect densities of the linker/CH3 modified surfaces are dependent on the coverage and composition of the organic layer. Surface recombination velocity (SRV) measurements indicated that n-Si(111)-8a/CH3 and the ferrocene coupled n-Si(111)-8a/CH3-Fc exhibited relatively high surface carrier lifetimes (4.51 and 3.88 μs, respectively) and correspondingly low S values (3880 and 4510 cm s(-1)). Thus, the multistep, linker/Fc functionalized surfaces exhibit analogously low trap state densities as compared to the fully passivated n-Si(111)-CH3 surface.

N-heterocyclic carbene-assisted, bis(phosphine)nickel-catalyzed cross-couplings of diarylborinic acids with aryl chlorides, tosylates, and sulfamates

Efficient bis(phosphine)nickel-catalyzed cross-couplings of diarylborinic acids with aryl chlorides, tosylates, and sulfamates have been effected with an assistance of N-heterocyclic carbene (NHC) generated in situ from N,N'-dialkylimidazoliums, e.g., N-butyl-N'-methylimidazolium bromide ([Bmim]Br), in toluene using K3PO4·3H2O as base. In contrast to bis(NHC)nickel-catalyzed conventional Suzuki coupling of arylboronic acids, mono(NHC)bis(phosphine)nickel species generated in situ from Ni(PPh3)2Cl2/[Bmim]Br displayed high catalytic activities in the cross-couplings of diarylborinic acids. The structural influences from diarylborinic acids were found to be rather small, while electronic factors from aryl chlorides, tosylates, and sulfamates affected the couplings remarkably. The couplings of electronically activated aryl chlorides, tosylates, and sulfamates could be efficiently effected with 1.5 mol % NiCl2(PPh3)2/[Bmim]Br as catalyst precursor to give the biaryl products in excellent yields, while 3-5 mol % loadings had to be used for the couplings of non- and deactivated ones. A small ortho-substitutent on the aromatic ring of aryl chlorides, tosylates, and sulfamates was tolerable. Applicability of the nickel-catalyzed cross-couplings in practical synthesis of fine chemicals has been demonstrated in process development for a third-generation topical retinoid, Adapalene.

Discovery of orteronel (TAK-700), a naphthylmethylimidazole derivative, as a highly selective 17,20-lyase inhibitor with potential utility in the treatment of prostate cancer

A novel naphthylmethylimidazole derivative 1 and its related compounds were identified as 17,20-lyase inhibitors. Based on the structure-activity relationship around the naphthalene scaffold and the results of a docking study of 1a in the homology model of 17,20-lyase, the 6,7-dihydro-5H-pyrrolo[1,2-c]imidazole derivative (+)-3c was synthesized and identified as a potent and highly selective 17,20-lyase inhibitor. Biological evaluation of (+)-3c at a dose of 1mg/kg in a male monkey model revealed marked reductions in both serum testosterone and dehydroepiandrosterone concentrations. Therefore, (+)-3c (termed orteronel [TAK-700]) was selected as a candidate for clinical evaluation and is currently in phase III clinical trials for the treatment of castration-resistant prostate cancer.