Novel and Mild Route to Phthalocyanines and 3-Iminoisoindolin-1-onesvia N,N-Diethylhydroxylamine-Promoted Conversion of Phthalonitriles and a Dramatic Solvent-Dependence of the Reaction

Pharmacophore Modeling and 3D-QSAR Study of Indole and Isatin Derivatives as Antiamyloidogenic Agents Targeting Alzheimer's Disease

Thirty-six novel indole-containing compounds, mainly 3-(2-phenylhydrazono) isatins and structurally related 1H-indole-3-carbaldehyde derivatives, were synthesized and assayed as inhibitors of beta amyloid (Aβ) aggregation, a hallmark of pathophysiology of Alzheimer's disease. The newly synthesized molecules spanned their IC50 values from sub- to two-digit micromolar range, bearing further information into structure-activity relationships. Some of the new compounds showed interesting multitarget activity, by inhibiting monoamine oxidases A and B. A cell-based assay in tau overexpressing bacterial cells disclosed a promising additional activity of some derivatives against tau aggregation. The accumulated data of either about ninety published and thirty-six newly synthesized molecules were used to generate a pharmacophore hypothesis of antiamyloidogenic activity exerted in a wide range of potencies, satisfactorily discriminating the 'active' compounds from the 'inactive' (poorly active) ones. An atom-based 3D-QSAR model was also derived for about 80% of 'active' compounds, i.e., those achieving finite IC50 values lower than 100 μM. The 3D-QSAR model (encompassing 4 PLS factors), featuring acceptable predictive statistics either in the training set (n = 45, q2 = 0.596) and in the external test set (n = 14, r2ext = 0.695), usefully complemented the pharmacophore model by identifying the physicochemical features mainly correlated with the Aβ anti-aggregating potency of the indole and isatin derivatives studied herein.

Insight into the binding mode of HIF-2 agonists through molecular dynamic simulations and biological validation

Hypoxia-inducible factor-2 (HIF-2), a heterodimeric transcriptional protein consisting of HIF-2α and aryl hydrocarbon receptor nuclear translocator (ARNT) subunits, has a broad transcriptional profile that plays a vital role in human oxygen metabolism. M1001, a HIF-2 agonist identified by high-throughput screening (HTS), is capable of altering the conformation of Tyr281 of the HIF-2α PAS-B domain and enhancing the affinity of HIF-2α and ARNT for transcriptional activation. M1002, an analog of M1001, shows improved efficacy than M1001. However, the cocrystal structure of M1001 and HIF-2 has some defects in revealing the agonist binding mode due to the relatively low resolution, while the binding mode of M1002 remained unexplored. To in-depth understand agonist binding profiles, herein, the molecular dynamic (MD) simulations was applied to construct a stable agonist-protein model, and a possible binding mode was proposed through the analysis of the binding free energy and hydrogen bonding of the simulation results. Nine compounds were then synthesized and evaluated to verify the proposed binding mode. Among them, compound 10 manifested improved agonistic activity and reduced toxicity compared to M1002. This study provides deep insight into the binding mode of such HIF-2 agonists, which would be useful for designing novel agonists for HIF-2.

Platinum Complexes with Chelating Acyclic Aminocarbene Ligands Work as Catalysts for Hydrosilylation of Alkynes

This work describes the preparation of a series of platinum-aminocarbene complexes [PtCl{C(N=C a (C6R2R3R4R5CON b ))=N(H)R1}(CNR1)] a-b (8-19, 65-75% isolated yield) via the reaction of cis-[PtCl2(CNR1)2] (R1 = Cy 1, t-Bu 2, Xyl 3, 2-Cl-6-MeC6H3 4) with 3-iminoisoindolin-1-ones HN=C a (C6R2R3R4R5CON b H) (R2-R5 = H 5; R3 = Me, R2, R4, R5 = H 6; R3, R4 = Cl, R2, R5 = H 7). New complexes 17-19 were characterized by elemental analyses (C, H, N), ESI+-MS, Fourier transform infrared spectroscopy (FT-IR), one-dimensional (1H, 13C{1H}), and two-dimensional (1H,1H correlation spectroscopy (COSY), 1H,13C heteronuclear multiple quantum correlation (HMQC)/1H,13C heteronuclear single quantum coherence (HSQC), 1H,13C heteronuclear multiple bond correlation (HMBC)) NMR spectroscopy, and authenticity of known species 8-16 was confirmed by FT-IR and 1H and 13C{1H} NMR. Complexes 8-19 were assessed as catalysts for hydrosilylation of terminal alkynes with hydrosilanes to give vinyl silanes, and complex [PtCl{C(N=C a (C6H3(5-Me)CON b ))=N(H)(2-Cl-6-MeC6H3)}{CN(2-Cl-6-MeC6H3)}] a-b (18) showed the highest catalytic activity. The catalytic system proposed operates at 80-100 °C for 4-6 h in toluene and with catalyst loading of 0.1 mol %, enabling the reaction of a number of terminal alkynes (PhC≡CH, t-BuC≡CH, and 4-(t-Bu)C6H4C≡CH) with hydrosilanes (Et3SiH, Pr3SiH, i-Pr3SiH, and PhMe2SiH). Target vinyl silanes were prepared in 48-95% yields (as a mixture of α/β isomers) and with maximum turnover number of 8.4 × 103. Hydrosilylation of internal alkynes (PhC≡CPh, Me(CH2)2C≡C(CH2)2Me, and PhC≡CMe) with hydrosilanes (Et3SiH, PhMe2SiH) led to the corresponding trisubstituted silylated alkenes in 86-94% yields. Initial observations on the mechanism of the catalytic action of platinum-ADC catalysts 8-19 suggested a molecular catalytic cycle.

Aza boron-pyridyl-isoindoline analogues: synthesis and photophysical properties

The synthesis and properties of four aza boron pyridyl-isoindoline analogues that differ in the position of fused benzene ring annelation on the pyridyl moiety is reported.

DDQ-mediated oxidative coupling: an approach to 2,3-dicyanofuran (thiophene)

A facile oxidative coupling of α-carbonyl radicals to 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) for the synthesis of 2,3-dicyanofurans and thiophenes starting from readily available β-diketones, simple ketones, and β-keto thioamides in up to 95% yield in one step was developed. Mechanistic investigations revealed that a radical process could be involved in this transformation, and a water promoted C-C bond cleavage pathway is proposed for the formation of 2,3-dicyanofurans and thiophenes.

Dialkylcyanamides are more reactive substrates toward metal-mediated nucleophilic addition than alkylcyanides

The dialkylcyanamide complexes Q[PtCl3(NCNR2)] (Q = Ph3PCH2Ph, R2 = Me21, Et22, C5H103, C4H8O 4; Q = NMe4, R2 = Me25; Q = NEt4, R2 = Me26) were synthesized either by dissolving Q2[Pt2(μ-Cl)2Cl4] in neat NCNR2 (1-4) or by substitution of a NCNR2 ligand with Cl(-) in [PtCl2(NCNR2)2] by its treatment with QCl (5, 6). Nucleophilic addition of dibenzylhydroxylamine, HON(CH2Ph)2, to 1-6 results in the formation of the complexes Q[PtCl3{NHC(NR2)ON(CH2Ph)2}] (Q = Ph3PCH2Ph, R2 = Me2, 7; Et2, 8; C5H10, 9; C4H8O, 10; Q = Me4N, R2 = Me211; Q = Et4N, R2 = Me2, 12) that further convert at room temperature in the solid state (1-24 h) or in a solution (0.5-2 h) to the imine complexes Q[PtCl3{N(CH2Ph)=C(H)Ph}] (Q = Ph3PCH2Ph, 13; Me4N, 14; Et4N, 15) and the corresponding dialkylureas H2NC(=O)NR2. The competitive reactivity study of the nucleophilic addition of HON(CH2Ph)2 to (Ph3PCH2Ph)[PtCl3(NCR')] (R' = Ph, NR2, CH2Ph) indicated that the reactivity of the coordinated NCNR2 is comparable to NCPh, while NCCH2Ph appeared to be much less reactive than the former two ligands. Compounds 1-6 and 13 were fully characterized by elemental analyses (C, H, N), high resolution ESI-MS, IR, and (1)H and (13)C{(1)H} NMR spectroscopy. The structure of 1 was additionally verified by a single-crystal X-ray diffraction.

Rhodium-catalyzed annulation of N-benzoylsulfonamide with isocyanide through C-H activation

Isocyanide insertion: the first rhodium-catalyzed annulation of N -benzoylsulfonamide incorporating with isocyanide via C-H activation is described. The transformation is broadly compatible with N -benzoylsulfonamides bearing various electron-properties as well as isocyanides. From practical point of view, this methodology provides the most straightforward approach to a series of 3-(imino)isoindolinones.