Stereoselective Synthesis of Quaternary Benzylic Carbons Using C2 Symmetric Imidazolines and Tetrahydrofuran as Electrophile

1,3-Disubstituted-1,2,4-triazin-6-ones with potent activity against androgen receptor-dependent prostate cancer cells

Synthesis and biological evaluation of a small, focused library of 1,3-disubstituted-1,2,4-triazin-6-ones for in vitro inhibitory activity against androgen-receptor-dependent (22Rv1) and androgen-receptor independent (PC3) castration-resistant prostate cancer (CRPC) cells led to highly active compounds with in vitro IC50 values against 22Rv1 cells of <200 nM, and with apparent selectivity for this cell type over PC3 cells. From metabolic/PK evaluations of these compounds, a 3-benzyl-1-(2,4-dichlorobenzyl) derivative had superior properties and showed considerably stronger activity, by nearly an order of magnitude, against AR-dependent LNCaP and C4-2B cells compared to AR-independent DU145 cells. This lead compound decreased AR expression in a dose and time dependent manner and displayed promising therapeutic effects in a 22Rv1 CRPC xenograft mouse model. Computational target prediction and subsequent docking studies suggested three potential known prostate cancer targets: p38a MAPK, TGF-β1, and HGFR/c-Met, with the latter case of c-Met appearing stronger, owing to close structural similarity of the lead compound to known pyridazin-3-one derivatives with potent c-Met inhibitory activity. RNA-seq analysis showed dramatic reduction of AR signalling pathway and/or target genes by the lead compound, subsequently confirmed by quantitative PCR analysis. The lead compound was highly inhibitory against HGF, the c-Met ligand, which fitted well with the computational target prediction and docking studies. These results suggest that this compound could be a promising starting point for the development of an effective therapy for the treatment of CRPC.

Synthesis of CF3-Containing 2-Imidazolines and Imidazoles via a Iodide-Promoted [3 + 2] Cyclization Reaction

We report herein a general and effective system achieving cyclization of β-trifluoromethyl enones with amidines in the presence of 1,3-diiodo-5,5-dimethylhydantoin (DIH), which affords a range of trifluoromethylated 2-imidazolines in synthetically useful yields with good diastereoselectivities (up to 95% yield, up to 98:2 dr) and good functional group tolerance. Furthermore, the one-pot synthesis of trifluoromethylated imidazoles via sequential cyclization and oxidation is demonstrated. More significantly, the reaction mechanism was verified by ESI-MS studies of possible intermediates, and a reasonable reaction mechanism was proposed.

The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines

A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines and N-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.

Electrochemical tandem trifluoromethylation of allylamines/formal (3 + 2)-cycloaddition for the rapid access to CF3-containing imidazolines and oxazolidines

A straightforward and environmentally friendly synthesis of CF₃-containing imidazolines and oxazolidines has been developed through an electrochemical three-component reaction among allylamines, the Langlois reagent, and nitrile or carbonyl compounds.

Unexpected lateral-lithiation-induced alkylative ring opening of tetrahydrofurans in deep eutectic solvents: synthesis of functionalised primary alcohols

o-Tolyl-substituted tetrahydrofurans undergo highly regioselective ring opening with the concomitant formation of new C-C bonds as the result of a lateral lithiation reaction. This reaction provides a new method for the synthesis of functionalised primary alcohols and can be run directly in protic eutectic mixtures as benign reaction media at 0 °C and under air, competitively with protonolysis.

Metal-free one-pot synthesis of 1,3-diazaheterocyclic compounds via I2-mediated oxidative C–N bond formation

A variety of 1,3-diazaheterocyclic compounds, including quinazolinones, benzimidazoles, and cyclic amidines, were readily synthesized through this metal-free one-pot annulation reaction.

Rational Design of Sterically and Electronically Easily Tunable Chiral Bisimidazolines and Their Applications in Dual Lewis Acid/Brønsted Base Catalysis for Highly Enantioselective Nitroaldol (Henry) Reactions

A new addition to the rational design of sterically and electrically easily tunable chiral bis(imidazoline) ligands from chiral amino alcohols has been developed. Vast structural variation of chiral bis(imidazoline) ligands can be simply achieved by the choice of both the 1,2-amino alcohol and its N-1 R1 substituent. A small library of chiral bisimidazolines (1 a-h) has been constructed. The method has provided an easy and simplified route to a diverse set of air-stable and water-tolerant chiral bis(imidazoline) ligands on 10 g scales. The dual Lewis Acid/Brønsted base catalytic system generated from the (S)-1 a/Cu(OTf)2 complex and Et3N was able to catalyze Henry reactions between aldehydes and nitromethane effectively at room temperature, and also to tolerate a wide scope of aldehydes with excellent enantiomeric excesses. Not only aromatic aldehydes but also aliphatic aldehydes afforded the nitroalcohol products, with enantiomeric excesses in the 93-98% range. This dual catalytic system is among the most effective systems so far reported for the asymmetric parent Henry reactions. This work also represents the first members of the class of chiral bisimidazolines to have been demonstrated to achieve excellent enantioselectivities.

Highly efficient enantiospecific synthesis of imidazoline-containing amino acids using bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate

A highly efficient enantiospecific synthesis of imidazoline-based amino acids is reported from dipeptides composed of a C-terminal beta-amino-alpha-amino acid residue using bis(triphenyl) oxodiphosphonium trifluoromethanesulfonate. These imidazolines were easily converted to imidazoles and incorporated into macrolactam analogues of bistratamide H without loss of stereochemical integrity.

Synthesis of Enantiopure Imidazolines through a Ritter Reaction of 2-(1-Aminoalkyl)aziridines with Nitriles

The Ritter reaction of enantiopure 2-(1-aminoalkyl)aziridines 1 with different nitriles afford enantiopure tetrasubstituted imidazolines 2. The opening of the aziridine ring takes place with total regio- and stereoselectivity. A mechanism to explain the described addition reaction is proposed. [reaction: see text]

Effects of C2-Alkylation, N-Alkylation, and N,N‘-Dialkylation on the Stability and Estrogen Receptor Interaction of (4R,5S)/(4S,5R)-4,5-Bis(4-hydroxyphenyl)-2-imidazolines

(4R,5S)/(4S,5R)-4,5-Bis(4-hydroxyphenyl)-2-imidazolines bearing 2,2'-H (3a), 2,2'-Cl (3b), 2,2',6-Cl (3c), and 2,2'-F (3d) substituents in the aromatic rings were C2-alkylated (5a-i), N-alkylated (7, 7a-c), and N,N'-dialkylated (9a-c). The synthesis started from the diastereomerically pure (1R,2S)/(1S,2R)-1,2-diamino-1,2-bis(4-methoxyphenyl)ethanes 1a-d, which were cyclized to the imidazolines 2a-d and 4a-i with triethylorthoesters or iminoethers. Ether cleavage with BBr(3) yielded the (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines 3a-d and 5a-i. The N-alkylation and N,N'-dialkylation of 2b, employed for obtaining 7a-c and 9a-c, were performed prior to the ether cleavage with alkyl iodine in dry THF. By use of HPLC, the influence of the substitution patterns in the aromatic rings and alkyl chains at the C2- or N-atoms on the hydrolysis rate of the imidazolines was studied under in vitro conditions. It appeared that only imidazolines with C2- or N-alkyl substituents show sufficient stability to interact as heterocycles with the estrogen receptor (ER). The resulting gene activation was monitored in a luciferase assay using ERalpha-positive MCF-7-2a breast cancer cells stably transfected with the plasmid ERE(wtc)luc. It is interesting to note that C2-alkylation led to a strong reduction or even a complete loss of activity whereas N-alkylation improved the estrogenic profile. The (4R,5S)/(4S,5R)-N-ethyl-4,5-bis(2-chloro-4-hydroxyphenyl)-2-imidazoline 7b has proven to be the most active compound in this structure-activity relationship study (EC(50) = 0.015 microM).