Controllable 1,3-Bis-Functionalization of 2-Nitroglycals with High Regioselectivity and Stereoselectivity Enabled by a H-Bond Catalyst.

The selective modification of carbohydrates is significant for producing their unnatural analogues for drug discovery. C1-functionalization (glycosylation) and C1,C2-difunctionalization of carbohydrates have been well developed. In contrast, C3-functionalization or C1,C3-difunctionalization of carbohydrates remains rare. Herein, we report such processes that efficiently and stereoselectively modify carbohydrates. Specifically, we found that trifluoroethanol (TFE) could promote 1,3-bis-indolylation/pyrrolylation of 2-nitroglycals generated carbohydrate derivatives in up to 93% yield at room temperature; slightly reducing the temperature could install two different indoles at the C1- and C3-positions. Switching TFE to a bifunctional amino thiourea catalyst leads to the generation of C3 monosubstituted carbohydrates, which could also be used to construct 1,3-di-C-functionalized carbohydrates. This approach produced a range of challenging sugar derivatives (over 80 examples) with controllable and high stereoselectivity (single isomer for over 90% of the examples). The potential applications of the reaction were demonstrated by a set of transformations including the synthesis of bridged large-ring molecules and gram scale reactions. Biological activities evaluation demonstrated that three compounds exhibit a potent inhibitory effect on human cancer cells T24, HCT116, AGS, and MKN-45 with IC50 ranged from 0.695 to 3.548 µM.

One-pot cascade synthesis of dibenzothiophene-based heterobiaryls from dibenzothiophene-5-oxide.

A sulfoxide directed C-H metalation/boration/B2Pin2 mediated reduction/Suzuki coupling process to synthesize 4-substituted dibenzothiophene (DBT) in one-pot from dibenzothiophene-5-oxide (DBTO) was developed. A variety of DBT-based heterobiaryls were prepared in satisfactory to good yields. A mechanism was proposed. The application of this methodology was demonstrated by synthesizing a luminescent material.

Design, synthesis and structure-activity relationship studies on erianin analogues as pyruvate carboxylase inhibitors in hepatocellular carcinoma cells.

A series of novel erianin analogues were designed and synthesized based on the bioisosterism principle by altering the two aromatic rings of erianin, the substituents on the rings and the linker between them. The analogues were evaluated as pyruvate carboxylase (PC) inhibitors in hepatocellular carcinoma cells. It was found that compounds 35 and 36, where fluorine replaces a hydroxyl group, exhibited higher activity than erianin (IC50 value of 17.30 nM) in liver cancer cells with IC50 values of 15.15 nM and 10.05 nM, respectively. Additionally, at a concentration of 10 nM, compounds 35 and 36 inhibited PC with inhibitory rates of 39.10% and 40.15%, respectively, exhibiting nearly identical inhibitory activity to erianin (inhibitory rate of 40.07%). Additionally, a computer simulation docking study demonstrated the basis for better interactions between the receptors and ligands. The fluorine atom of 35 can not only form hydrogen bonds with Lys-1043 (NH⋯F, 2.04 Å), but also form fluorine bonds with the carbonyl groups of Lys-1043 (3.67 Å) and Glu-1046 (3.70 Å), due to the different orientations of the halogens on the B ring warhead. Conversely, the chlorine atom of 34 can only form alkyl hydrophobic interactions with the alkane chain in Lys-1043. Fluorinated compounds 35 and 36 also show better chemical stability and higher log P (clog P = 3.89 for 35 and 36) values than that of erianin (clog P = 3.07), and may be used as candidate compounds for further drug development.

Regioselective Synthesis of Pyrazolo[1,5-a]pyridine via TEMPO-Mediated [3 + 2] Annulation-Aromatization of N-Aminopyridines and α,ß-Unsaturated Compounds.

A TEMPO-mediated [3 + 2] annulation-aromatization protocol for the preparation of pyrazolo[1,5-a]pyridines from N-aminopyridines and α,ß-unsaturated compounds was developed. The procedure offered multisubstituted pyrazolo[1,5-a]pyridines in good to excellent yield with high and predictable regioselectivity. The modification of marketed drugs including Loratadine, Abiraterone, and Metochalcone, and a one-pot three-step gram scale synthesis of key intermediate for the preparation of Selpercatinib were demonstrated. Mechanism studies show that TEMPO serves both as a Lewis acid and as an oxidant.

Discovery of 3,4-Dihydrobenzo[f][1,4]oxazepin-5(2H)-one Derivatives as a New Class of Selective TNIK Inhibitors and Evaluation of Their Anti-Colorectal Cancer Effects.

The Traf2- and Nck-interacting protein kinase (TNIK) is a downstream signal protein of the Wnt/ß-catenin pathway and has been thought of as a potential target for the treatment of colorectal cancer (CRC) that is often associated with dysregulation of Wnt/ß-catenin signaling pathway. Herein, we report the discovery of a series of 3,4-dihydrobenzo[f][1,4]oxazepin-5(2H)-one derivatives as a new class of TNIK inhibitors. Structure-activity relationship (SAR) analyses led to the identification of a number of potent TNIK inhibitors with compound 21k being the most active one (IC50: 0.026 ± 0.008 µM). This compound also displayed excellent selectivity for TNIK against 406 other kinases. Compound 21k could efficiently suppress CRC cell proliferation and migration in in vitro assays and exhibited considerable antitumor activity in the HCT116 xenograft mouse model. It also showed favorable pharmacokinetic properties. Overall, 21k could be a promising lead compound for drug discovery targeting TNIK and deserves further studies.

Discovery of thieno[2,3-d]pyrimidin-4(3H)-one derivatives as a new class of ROCK inhibitors.

Herein, we report the discovery of a series of thieno[2,3-d]pyrimidin-4(3H)-one derivatives as a new class of ROCK inhibitors. Structure-activity relationship studies of these compounds led to the identification of the most potent compound, 3-(3-methoxybenzyl)-6-(1H-pyrrolo[2,3-b]pyridin-4-yl)thieno[2,3-d]pyrimidin-4(3H)-one (8k), which showed IC50 values of 0.004 µM and 0.001 µM against ROCK Ⅰ and ROCK Ⅱ, respectively. In vitro, 8k significantly reduced the phosphorylation level of ROCK downstream signaling protein and induce changes in cell morphology and migration. Overall, this study provides a promising lead compound for drug discovery targeting ROCKs.

Discovery of 4H-Chromen-4-one Derivatives as a New Class of Selective Rho Kinase (ROCK) Inhibitors, which Showed Potent Activity in ex Vivo Diabetic Retinopathy Models.

Diabetic retinopathy (DR) is a major cause of blindness, and there is a lack of effective treatment at present. Rho-associated coiled-coil containing serine/threonine protein kinases (ROCKs) have recently been suggested as potential targets for the DR treatment. We herein report the discovery of 4H-chromen-4-one derivatives as a new class of ROCK inhibitors. Structure-activity relationship analyses led to the identification of the most active compound, 4-(dimethylamino)-N-(3-{2-[(4-oxo-4H-chromen-7-yl)oxy]acetamido}phenyl) (12j). This compound showed excellent kinase selectivity for ROCK I and ROCK II against 387 other kinases. In retinal explants, compound 12j protected retinal neurons from high glucose-induced oxidative stress and apoptosis-mediated cell death. Furthermore, 12j administration suppressed the improper proliferation of Müller cells and promoted the regression of vascular vessels in retinal explants cultured in a high glucose microenvironment. Collectively, our data suggest that 12j could be a potential lead compound for the treatment of DR, hence deserving further in-depth studies.

Identification of 5-(2,3-Dihydro-1 H-indol-5-yl)-7 H-pyrrolo[2,3- d]pyrimidin-4-amine Derivatives as a New Class of Receptor-Interacting Protein Kinase 1 (RIPK1) Inhibitors, Which Showed Potent Activity in a Tumor Metastasis Model.

We herein report the structural optimization and structure-activity relationship studies of 5-(2,3-dihydro-1 H-indol-5-yl)-7 H-pyrrolo[2,3- d]pyrimidin-4-amine derivatives as a new class of receptor-interacting protein kinase 1 (RIPK1) inhibitors. Among all obtained RIPK1 inhibitors, 1-(5-{4-amino-7-ethyl-7 H-pyrrolo[2,3- d]pyrimidin-5-yl}-2,3-dihydro-1 H-indol-1-yl)-2-[3-(trifluoromethoxy)phenyl]ethan-1-one (22b) is the most active one. This compound potently inhibited RIPK1 with a binding affinity ( KD) of 0.004 µM and an enzymatic IC50 value of 0.011 µM and also showed good kinase selectivity. It could efficiently protect cells from necroptosis and attenuate the necrotic cell death of vascular endothelial cells induced by tumor cells both in vitro and in vivo. Importantly, compound 22b exhibited excellent antimetastasis activity in the experimental B16 melanoma lung metastasis model. It also displayed favorable pharmacokinetic properties. Collectively, 22b could be a promising agent for preventing tumor metastasis.