Fragment-based lead discovery of indazole-based compounds as AXL kinase inhibitors.

AXL is a member of the TAM (TYRO3, AXL, MER) subfamily of receptor tyrosine kinases. It is upregulated in a variety of cancers and its overexpression is associated with poor disease prognosis and acquired drug resistance. Utilizing a fragment-based lead discovery approach, a new indazole-based AXL inhibitor was obtained. The indazole fragment hit 11, identified through a high concentration biochemical screen, was expeditiously improved to fragment 24 by screening our in-house expanded library of fragments (ELF) collection. Subsequent fragment optimization guided by docking studies provided potent inhibitor 54 with moderate exposure levels in mice. X-ray crystal structure of analog 50 complexed with the I650M mutated kinase domain of Mer revealed the key binding interactions for the scaffold. The good potency coupled with reasonable kinase selectivity, moderate in vivo exposure levels, and availability of structural information for the series makes it a suitable starting point for further optimization efforts.

Study of substrate dependence on the chemoselectivity of the gold-catalysed cycloisomerisation of aryl substituted 1,7-enynes.

The effects of starting material substitution patterns on reaction selectivity for the gold(I)-catalysed cycloisomerisations of aryl substituted 1,7-enynes were investigated. The results indicated the chemoselectivity of the reaction to be highly substrate and catalyst dependent. Either the piperidine or the tetrahydro-1H-azepine product was obtained in moderate to excellent yields depending on the steric and/or electronic nature of the substrate and the gold(I) catalyst. Overall, six-membered nitrogen ring formation was found to be favoured in reactions with 1,7-enyne derivatives containing a disubstituted alkene moiety or not bearing a sterically bulky substituent or a gold(I) catalyst with a pendant sterically unencumbered phosphine ligand. Formation of the seven-membered nitrogen heterocycle was observed in reactions where the substrate contained a tetrasubstituted alkene unit or a sterically demanding substituent.

Cyclopropyl carbinol rearrangement for benzo-fused nitrogen ring synthesis.

A synthetic method that relies on gold-catalysed cyclopropyl carbinol rearrangement of 2-tosylaminophenyl cyclopropylmethanols to prepare 2,3-dihydro-1H-benzo[b]azepines and 2-vinylindolines efficiently is reported. The reactions were shown to be chemoselective, with secondary and tertiary alcohol substrates exclusively providing benzo-fused five- and seven-membered ring products, respectively. The ring-forming process was also found to proceed in moderate to excellent yields under mild conditions only in the presence of the gold and silver catalyst combination. The mechanism is thought to involve activation of the alcohol by the (p-CF(3)C(6)H(4))(3)PAuCl/AgOTf (Tf = triflate) catalyst, resulting in ionization of the starting material. The tertiary carbocationic intermediate generated in situ in this manner then triggers ring-opening of the cyclopropane moiety and trapping by the tethered aniline group to give the 2,3-dihydro-1H-benzo[b]azepine. Cyclopropane ring fragmentation of the secondary carbocationic analogue, on the other hand, results in diene formation followed by subsequent intramolecular hydroamination to afford the 2-vinylindoline.

Correction to "Discovery of Irreversible Inhibitors Targeting Histone Methyltransferase, SMYD3".

[This corrects the article DOI: 10.1021/acsmedchemlett.9b00170.].

Discovery of Irreversible Inhibitors Targeting Histone Methyltransferase, SMYD3.

SMYD3 is a histone methyltransferase that regulates gene transcription, and its overexpression is associated with multiple human cancers. A novel class of tetrahydroacridine compounds which inhibit SMYD3 through a covalent mechanism of action is identified. Optimization of these irreversible inhibitors resulted in the discovery of 4-chloroquinolines, a new class of covalent warheads. Tool compound 29 exhibits high potency by inhibiting SMYD3's enzymatic activity and showing antiproliferative activity against HepG2 in 3D cell culture. Our findings suggest that covalent inhibition of SMYD3 may have an impact on SMYD3 biology by affecting expression levels, and this warrants further exploration.