A novel class of "GABAergic" agents: 1-aryl-3-(aminoalkylidene)oxindoles

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

A highly modular method for the synthesis of (Z)-3-[amino(phenyl/methyl)methylidene]-1,3-dihydro-2H-indol-2-ones starting from easily available 3-bromooxindoles or (2-oxoindolin-3-yl)triflate and thioacetamides or thiobenzamides is described. A series of 49 compounds, several of which have previously been shown to possess significant tyrosin kinase inhibiting activity, was prepared in yields varying mostly from 70 to 97% and always surpassing those obtained by other published methods. The method includes an Eschenmoser coupling reaction, which is very feasible (even without using a thiophile except tertiary amides) and scalable. The (Z)-configuration of all products was confirmed by NMR techniques.

Ionic liquid-Accelerated N-Arylation of Benzoazoles with Diaryliodonium Salts, An Efficient Method for the Synthesis of N-aryl Azoles

N-Arylation of benzoazoles with diaryliodonium salts can be performed in good yields in the room-temperature ionic liquid 1–butyl–3–methylimidazolium tetrafluoroborate ([bmim]BF4), which provides an efficient method for the synthesis of N-arylbenzoazoles. The ionic liquid can be recycled and reused.

Enamino-oxindole HIV protease inhibitors

We have designed and synthesized a series of HIV protease inhibitors (PIs) with enamino-oxindole substituents optimized to interact with the S2' subsite of the HIV protease binding pocket. Several of these inhibitors have sub-nanomolar K(i) and antiviral IC(50) in the low nM range against WT HIV and against a panel of multi-drug resistant (MDR) strains.

2-Chloro-N,N-diphenyl-acetamide

In the title compound, C(14)H(12)ClNO, the central acetamide plane forms dihedral angles of 76.0 (2) and 64.0 (2)° with the phenyl rings and the phenyl rings form a dihedral angle of 71.8 (2)° with each other.

Orthogonal Pd- and Cu-based catalyst systems for C- and N-arylation of oxindoles

In the cross-coupling reactions of unprotected oxindoles with aryl halides, Pd- and Cu-based catalyst systems displayed orthogonal chemoselectivity. A Pd-dialkylbiarylphosphine-based catalyst system chemoselectively arylated oxindole at the 3 position, while arylation occurred exclusively at the nitrogen using a Cu-diamine-based catalyst system. Computational examination of the relevant L1Pd(Ar)(oxindolate) and diamine-Cu(oxindolate) species was performed to gain mechanistic insight into the controlling features of the observed chemoselectivity.

Design, synthesis and in vivo anticonvulsant screening in mice of Novel phenylacetamides

A set of seven novel N-substituted 2-anilinophenylacetamides were designed by pharmacophore generation and using flexible alignment module of MOE software. The novel molecules were synthesized and screened for anticonvulsant activity in Swiss albino mice by MES and ScPTZ induced seizure tests. Test compounds were found to be potent in MES test. Compounds 12 and 14 were found to be more potent with ED(50) values 24.0 and 8.0 mg kg(-1), respectively, and their activity was comparable to standard drugs (Phenytoin, Carbamazepine). Test compounds did not show significant activity in ScPTZ test. Compounds 12 and 14 also exhibited higher protective indices (20.3 and 87.5, respectively) when assessed for neurotoxicity by rotarod test as compared to the standards.

Design of novel bioisosteres of beta-diketo acid inhibitors of HIV-1 integrase

HIV-1 integrase (IN) is an attractive and validated target for the development of novel therapeutics against AIDS. Significant efforts have been devoted to the identification of IN inhibitors using various methods. In this context, through virtual screening of the NCI database and structure-based drug design strategies, we identified several pharmacophoric fragments and incorporated them on various aromatic or heteroaromatic rings. In addition, we designed and synthesized a series of 5-aryl(heteroaryl)-isoxazole-3-carboxylic acids as biological isosteric analogues of beta-diketo acid containing inhibitors of HIV-1 IN and their derivatives. Further computational docking studies were performed to investigate the mode of interactions of the most active ligands with the IN active site. Results suggested that some of the tested compounds could be considered as lead compounds and suitable for further optimization.

Concise syntheses of the cruciferous phytoalexins brassilexin, sinalexin, wasalexins, and analogues: expanding the scope of the vilsmeier formylation

Efficient syntheses of the phytoalexins brassilexin, sinalexin, and analogues are demonstrated through the application of the Vilsmeier formylation to indoline-2-thiones followed by a new aqueous ammonia workup procedure. Similarly, a very concise two-pot synthesis of the phytoalexins wasalexins using sequential formylation-amination of indolin-2-ones is described. Remarkably, this novel aqueous ammonia workup allows the sequential one-pot formylation-amination, expanding substantially the scope of the Vilsmeier formylation of both indoline-2-thiones and indolin-2-ones. The examination of the formylation-amination reaction and optimization of conditions, as well as the syntheses and antifungal activities of several brassilexin analogues, are reported.

Single-photon emission computed tomography in neurotherapeutics

The measurement of regional cerebral blood flow (rCBF) by single-photon emission computed tomography (SPECT) is a powerful clinical and research tool. There are several clinical applications now documented, a substantial number under active investigation, and a larger number yet to be studied. Standards regarding patient imaging environment and image presentation are becoming established. This article reviews key aspects of SPECT functional brain imaging in clinical practice, with a particular emphasis on therapeutics, including 1) the quality of the tomographic device, 2) the radiopharmaceutical employed, 3) environmental conditions at the time of radiotracer administration, 4) characteristics of the subject, 5) the format used for image presentation, and 6) the essential components of image processing necessary to the achievement of high-quality SPECT brain images. Next, a brief description of relevant radiation safety issues is provided. Finally, applications in molecular imaging, especially in small animal imaging for research as well as drug discovery and development are discussed. The gamut of SPECT studies from currently routine clinical applications to molecular imaging offers a wonderful frontier for opportunities to employ functional brain imaging in neurotherapeutics.

Amination reactions of aryl halides with nitrogen-containing reagents mediated by palladium/imidazolium salt systems

Nucleophilic N-heterocyclic carbenes have been conveniently used as catalyst modifiers in amination reactions involving aryl chlorides, aryl bromides, and aryl iodides with various nitrogen-containing substrates. The scope of a coupling process using a Pd(0) or Pd(II) source and an imidazolium salt in the presence of a base, KO(t)Bu or NaOH, was tested using various substrates. The Pd(2)(dba)(3)/IPr.HCl (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) system presents the highest activity with respect to electron-neutral and electron-rich aryl chlorides. The ligand is also effective for the synthesis of benzophenone imines, which can be easily converted to the corresponding primary amines by acid hydrolysis. Less reactive indoles were converted to N-aryl-substituted indoles using as supporting ligand the more donating SIPr.HCl (5, SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). The Pd(OAc)(2)/SIPr.HCl/NaOH system is efficient for the N-arylation of diverse indoles with aryl bromides. The general protocol developed has been applied successfully to the synthesis of a key intermediate in the synthesis of an important new antibiotic. Mechanistically, palladium-to-ligand ratio studies strongly support an active species bearing one nucleophilic carbene ligand.

Technetium(V) oxo complexes of substituted propylene diamine dioxime (PnAO) ligands: water-dependent interconversion between syn and anti isomers

99mTc and (99)Tc complexes of PnAO (propylene diamine dioxime) ligands monosubstituted in the 6-position [PnAO-6-R] were prepared and studied. Ligands substituted with an alkyl group or with no substituent (R = H, CH(3), or CH(2)CH(CH(3))(2)), gave only one Tc complex. However, for several other nonalkyl substituents (R = COOCH(3), OH, OCH(3), OCH(2)CH(3), F, CN, NHCOCH(3), and NHCOCH(2)CH(3)), two Tc complexes A and B were formed. Products A and B were assigned to the anti and syn TcO(PnAO-6-R) species, respectively, based on (1)H NMR results. X-ray structure analyses supported these assignments. The A (anti) isomer of TcO(PnAO-6-OH) had the chemical formula TcC(13)H(25)N(4)O(4) and crystallized in an orthorhombic system with space group P2(1)2(1)2(1) and Z = 4; a = 12.744(2) A, b = 13.591(2) A, c = 9.976(2) A. The B (syn) isomer of TcO(PnAO-6-CN) had the chemical formula TcC(14)H(24)N(5)O(3) and was a 1:4 mixture of two monoclinic polymorphs: individual rectangular prisms (space group P2(1)/c, Z = 4) and clusters of intergrown twinned rectangular rods (space group Cc, Z = 8). For the prisms, a = 12.457(1) A, b = 13.932(1) A, c = 10.336(1) A, and for the rods, a = 31.344(5) A, b = 6.993(1) A, c = 21.657(2) A. The syn and anti isomers interconverted in the presence of water; nonequilibrium mixtures of epimers remained unchanged under dry conditions. The HPLC behavior under reversed phase conditions was consistent with on-column interconversion (poor resolution), whereas the two isomers were cleanly resolved under drier normal phase conditions. An oxo inversion mechanism involving trans water attack is proposed for the interconversion process. Water also influenced the position of equilibrium of the two isomers. The syn isomer was stabilized in water relative to the anti isomer.

Synthesis and characterization of mixed-ligand oxorhenium complexes with the SNN type of ligand. Isolation of a novel ReO[SN][S][S] complex

A new series of mixed-ligand oxorhenium complexes 4-9, with ligands 1-3 (L1H2) containing the SNN donor set and monodentate thiols as coligands (L2H), is reported. All complexes were synthesized using ReOCl3(PPh3)2 as precursor. They were isolated as crystalline products and characterized by elemental analysis and IR and NMR spectroscopy. The ligands 1 and 2 (general formula RCH2CH2NHCH2CH2SH, where R = N(C2H5)2 in 1 and pyrrolidin-1-yl in 2) act as tridentate SNN chelates to the ReO3+ core, leaving one open coordination site cis to the oxo group. The fourth coordination site is occupied by a monodentate aromatic thiol which acts as a coligand. Thus, three new "3 + 1" [SNN][S] oxorhenium complexes 4-6 (general formula ReO[RCH2CH2NCH2CH2S][SX], where R = N(C2H5)2 and X = phenyl in 4, R = N(C2H5)2 and X = p-methylphenyl in 5, and R = pyrrolidinlyl and X = p-methylphenyl in 6) were prepared in high yield. Complex 4 adopts an almost perfect square pyramidal geometry (tau = 0.07), while 6 forms a distorted square pyramidal geometry (tau = 0.24). In both complexes 4 and 6, the basal plane is formed by the SNN donor set of the tridentate ligand and the S of the monodentate thiol. On the other hand, the ligand 3, [(CH3)2CH]2NCH2CH2NHCH2CH2SH, acts as a bidentate ligand, probably due to steric hindrance, and it coordinates to the ReO3+ core through the SN atoms, leaving two open coordination sites cis to the oxo group. These two vacant positions are occupied by two molecules of the monodentate thiol coligand, producing a novel type of "2 + 1 + 1" [SN][S][S] oxorhenium mixed-ligand complexes 7-9 (general formula ReO[[(CH3)2CH]2NCH2CH2NHCH2CH2S][SX][SX], where X = phenyl in 7, p-methylphenyl in 8, and benzyl in 9). The coordination sphere about rhenium in 7 and 8 consists of the SN donor set of ligand 3, two sulfurs of the two monodentate thiols, and the doubly bonded oxygen atom in a trigonally distorted square pyramidal geometry (tau = 0.44 and 0.45 for 7 and 8, respectively). Detailed NMR assignments were determined for complexes 5 and 8.

Efficient palladium-catalyzed N-arylation of indoles

[equation--see text] The N-arylation of indoles, including a variety of substituted ones, has been carried out using bulky, electron-rich phosphines as the supporting ligand in combination with Pd(2)(dba)(3). Using this catalyst system, the efficient coupling of indole and a variety of substituted indoles with aryl iodides, bromides, chlorides, and triflates can be achieved.

Technetium Complexes of a Hydrazinonicotinamide-Conjugated Cyclic Peptide and 2-Hydrazinopyridine: Synthesis and Characterization

Ternary ligand technetium complexes of a hydrazinonicotinamide-conjugated cyclic peptide (HYNICtide: cyclo(D-Val-NMeArg-Gly-Asp-Mamb(5-(6-(6-hydrazinonicotinamido)hexanamide)))) and 2-hydrazinopyridine (HYPY) were prepared and characterized by various spectroscopic methods. The HPLC concordance experiments for (99m)Tc and (99)Tc analogues show clearly that the same complexes are prepared on the no-carrier-added ((99m)Tc) and the carrier-added ((99)Tc) levels. Using a chirality experiment, it was demonstrated that the presence of two radiometric peaks in the HPLC chromatograms of RP444, RP445, and RP446 is due to the resolution of diastereomers, which result from the presence of chiral cyclic peptide and the formation of two enantiomers of the technetium chelate. In a ligand challenge experiment, we found that the high solution stability of these ternary ligand [(99m)Tc]HYNICtide complexes is due to their kinetic inertness. The 1:1:1:1 composition for Tc:HYNICtide:L:tricine (L = TPPTS, TPPDS, and TPPMS) in these ternary ligand [(99)Tc]HYNICtide complexes is confirmed by (1)H NMR and FAB mass spectral data and is completely consistent with that determined on the tracer ((99m)Tc) level. In addition, the IC(50) values of RP444, RP445, and RP446 and the two isomeric forms of RP444 were determined using a platelet IIb/IIIa binding assay. Both isomeric forms of RP444 were found to have the same binding affinity (IC(50) = 13 +/- 2 nM). Complexes [(99)Tc(HYPY)(PPh(3))(2)Cl(2)] and [(99)Tc(HYPY)(PPh(3))(tricine)] were isolated from the reaction of HYPY with [n-Bu(4)N][TcOCl(4)(-)] in the presence of excess tricine and triphenylphosphine. [(99)Tc(HYPY)(PPh(3))(tricine)] serves as a model for ternary ligand [(99m)Tc]HYNICtide complexes. Both complexes have been characterized by HPLC, spectroscopic (IR, NMR, and FAB-MS) methods, and elemental analysis. The HPLC concordance for complexes [(99m)Tc(HYPY)(PPh(3))(tricine)] and [(99)Tc(HYPY)(PPh(3))(tricine)] shows that the two complexes are identical. The NMR ((1)H and (13)C) data suggests that the complex [(99)Tc(HYPY)(PPh(3))(tricine)] have an octahedral coordination geometry with a monodentate diazenido HYPY, a tetradentate tricine, and a monodentate triphenylphosphine coligand.

Novel 99mTc aminobisthiolato/monothiolato "3 + 1" mixed ligand complexes: structure-activity relationships and preliminary in vivo validation as brain blood flow imaging agents

A series of neutral, lipophilic 99mTc mixed-ligand complexes of the general formula 99mTcOL1L2, where L1H2 is an N-substituted bis-(2-mercaptoethyl)amine, [X-CH2CH2N(CH2CH2SH)2], [SNS], and L2H is a monodentate thiol (RSH), [S], has been synthesized and evaluated in rodents for potential use in brain blood flow imaging. The complexes were prepared by ligand exchange reaction using 99mTc(V)O-glucoheptonate as precursor and equimolar quantities of the two ligands. In all cases the syn isomer was formed in a high yield, whereas the anti isomer was not always present. The formation of two isomeric complexes-syn and anti-was expected, since the N-substituent (X-CH2CH2N) can assume syn or anti configuration with respect to the 99mTcO3+ core during complexation. One anti and all syn isomers were isolated by HPLC. Their identity was confirmed by comparative HPLC studies with the analogous 99Tc complexes of established structure. In vivo distribution, in particular brain uptake and retention, greatly depended on the type of either tridentate (L1H2) or monodentate (L2H) ligand. All 99mTc complexes showed significant brain uptake in mice (0.78-4.35% injected dose per organ at 5 min postinjection). This initial uptake remained nearly constant for at least 30 min for most of the complexes. Structure-activity relationships of novel 99mTc(V)O SNS/S complexes in mice are reported and discussed. Selected complexes were further studied in rats. High brain uptake, comparable to that of 99mTc-d,l-HMPAO, and sufficient retention 60 min postinjection were provided with complex 18 [X = (C2H5)2N and R = p-CH3OC6H4CH2].