A parallel library of chiral ionic liquid (CIL)-modified silanes as potential chiral selectors was synthesized, and their enantiomeric discrimination abilities were screened by use of (19)F NMR spectroscopy. The screenin...A parallel library of chiral ionic liquid (CIL)-modified silanes as potential chiral selectors was synthesized, and their enantiomeric discrimination abilities were screened by use of (19)F NMR spectroscopy. The screening method allows for rapid identification of the most enantioselective members of the library and simultaneous investigation of their chiral recognition mechanisms. The library compounds were synthesized using quaternization and anion-exchange reactions. Three major parameters (type of chiral cations, anions, and linker chain lengths) were included and investigated during the synthesis and screening. As expected, the structure of the chiral cation was found to play an important role in determining chiral recognition abilities. In addition, several types of intermolecular interactions including ion-pair, hydrogen bonding, pi-pi stacking, dipole stacking, and steric interactions were found to impact chiral discrimination.
In the presence of Lawesson's reagent, metal-free one-pot cascade reactions of 2-iodoanilines with acid chlorides proceeded smoothly leading to 2-substituted benzothiazoles in good to excellent yields under mild conditio...In the presence of Lawesson's reagent, metal-free one-pot cascade reactions of 2-iodoanilines with acid chlorides proceeded smoothly leading to 2-substituted benzothiazoles in good to excellent yields under mild conditions. Three steps were involved in the reaction process: (1) 2-iodoanilines reacted with acid chlorides to afford benzamides, (2) benzamides transferred to benzothioamides in the presence of Lawesson's reagent, and (3) intramolecular cyclization of benzothioamides generated the expected benzothiazoles.
In this work, we report the synthesis of a combinatorial library of 80 derivatives of EDTA amide x-aminenaphthalene-y-sulfonic acid on four different supports with variable length linker. The sensing fluorescence behavio...In this work, we report the synthesis of a combinatorial library of 80 derivatives of EDTA amide x-aminenaphthalene-y-sulfonic acid on four different supports with variable length linker. The sensing fluorescence behavior of these materials for transitions metals was studied by packing the beads into a conventional flow-through cell in a continuous flow injection set up. The fluorescence emission response of these materials shows that sensors supported in Argopore (a) with the fluorescence moiety of 1-aminenaphthalene-4-sulfonic acid behaves like dosimeter for copper.
A traceless solid-phase synthesis of 6-amino- and 6-hydroxyimino-1,3,5-triazine-2,4-diones and 1,3,5-triazine-2,4,6-triones has been developed. The strategy comprises of linking a preformed N-carbamothioylcarbamate to br...A traceless solid-phase synthesis of 6-amino- and 6-hydroxyimino-1,3,5-triazine-2,4-diones and 1,3,5-triazine-2,4,6-triones has been developed. The strategy comprises of linking a preformed N-carbamothioylcarbamate to bromomethyl resin to give a S-linked isothiourea, which then undergoes cyclization with isocynates to yield the resin-bound 1,3,5-triazine-2,4-diones. Subsequent cleavage was accomplished by either direct substitution with a suitable amine or by oxidative activation of the thioether functionality followed by nucleophilic substitution. Using this synthetic strategy, we prepared a representative set of 31 6-amino-1,3,5-triazine-2,4-diones, 10 6-hydroxyimino-1,3,5-triazine-2,4-diones, and 8 1,3,5-triazine-2,4,6-triones.
The solution-phase synthesis of a 167-member library of isocoumarins is described. The key intermediates for library generation, 4-iodoisocoumarins, are easily prepared by iodocyclization of the corresponding 2-(1-alkyny...The solution-phase synthesis of a 167-member library of isocoumarins is described. The key intermediates for library generation, 4-iodoisocoumarins, are easily prepared by iodocyclization of the corresponding 2-(1-alkynyl)arenecarboxylate esters. The 4-iodoisocoumarins undergo palladium-catalyzed Sonogashira, Suzuki-Miyura, and Heck reactions to yield a diverse set of isocoumarins. Alternatively, isocoumarins, bearing hydroxyl or bromine functionalities, have been prepared by ZnCl(2)- and Pd(PPh(3))(4)-mediated cyclization of the corresponding o-iodobenzoic acid and appropriate terminal alkynes. The resulting isocoumarins were further diversified by derivatization of the hydroxyl or bromine groups. A small set of isoquinolinones were also prepared from the corresponding isocoumarins.
High-throughput biological assays were used to develop structure - antimicrobial relationships for polysiloxane coatings containing chemically bound (tethered) quaternary ammonium salt (QAS) moieties. The QAS-functional...High-throughput biological assays were used to develop structure - antimicrobial relationships for polysiloxane coatings containing chemically bound (tethered) quaternary ammonium salt (QAS) moieties. The QAS-functional polysiloxanes were derived from solution blends of a silanol-terminated polydimethylsiloxane, a trimethoxysilane-functional QAS (QAS-TMS), and methylacetoxysilane. Since the QAS moieties provide antimicrobial activity through interaction with the microorganism cell wall, most of the compositional variables that were investigated were associated with the chemical structure of the QAS-TMS. Twenty different QAS-TMS were synthesized for the study and the antimicrobial activity of sixty unique polysiloxane coatings derived from these QAS-TMS determined toward Escherichia coli , Staphylococcus aureus , and Candida albicans . The results of the study showed that essentially all of the compositional variables significantly influenced antimicrobial activity. Surface characterization of these moisture-cured coatings using atomic force microscopy as well as water contact angle and water contact angle hysteresis measurements indicated that the compositional variables significantly affected coating surface morphology and surface chemistry. Overall, compositional variables that produced heterogeneous surface morphologies provided the highest antimicrobial activity suggesting that the antimicrobial activity was primarily derived from the relationship between coating chemical composition and self-assembly of QAS moieties at the coating/air interface. Using data modeling software, a narrow region of the compositional space was identified that provided broad-spectrum antimicrobial activity.
Fluorous displaceable linker-facilitated synthesis of 1,4-benzodiazepine-2,5-dione library has been developed. Perfluorooctanesulfonyl protected 4-hydroxy benzaldehydes were used as the limiting agent for Ugi four-compon...Fluorous displaceable linker-facilitated synthesis of 1,4-benzodiazepine-2,5-dione library has been developed. Perfluorooctanesulfonyl protected 4-hydroxy benzaldehydes were used as the limiting agent for Ugi four-component reactions to form condensed products. Postcondensation reactions of the Ugi products generated 1,4-benzodiazepine-2,5-dione ring skeleton. Microwave-assisted Suzuki coupling reactions removed the fluorous tag and introduced biaryl functionality to the benzodiazepine ring. The library scaffold has four points of substitution diversities. The fluorous tag facilitated the intermediate purifications using fluorous solid-phase extraction (F-SPE) and had no negative impact on the reactivity of the Ugi reactions and postcondensation reactions.
The most efficient diversity generating approaches to heterocycles are combinations of a multicomponent (MCR) with a cyclization reaction, for example, by Ugi-deprotection-cylization (UDC) protocols. If the desired post-...The most efficient diversity generating approaches to heterocycles are combinations of a multicomponent (MCR) with a cyclization reaction, for example, by Ugi-deprotection-cylization (UDC) protocols. If the desired post-Ugi reaction requires more than one deprotection, for example of two initially protected Ugi-reactive groups, or if it requires additional activation, for example, by an Ugi-activation-cyclization (UAC), either the isolation of intermediates or a sequential process or both become necessary. A recently introduced convertible isonitrile reagent allows a mild and chemoselective in situ post-Ugi activation of the isonitrile-born carboxylate with simultaneous deprotection of the nucleophilic amine, that is, liberation and activation of two Ugi-reactive groups, if desired also under subsequent lactam formation. This is exemplified by the synthesis of peptide-peptoid diketopiperazines.
The efficient solid-phase synthesis of 3-hydroxy-2,7-disubstituted-6-nitroquinolin-4(1H)-ones using Rink amide resin is described. Synthesis starts from immobilized 4-chloro-5-nitroanthranilic acid which, after the nucle...The efficient solid-phase synthesis of 3-hydroxy-2,7-disubstituted-6-nitroquinolin-4(1H)-ones using Rink amide resin is described. Synthesis starts from immobilized 4-chloro-5-nitroanthranilic acid which, after the nucleophilic replacement of the chlorine atom with various amines and subsequent esterification with bromoacetophenones, afforded substituted phenacylanthranilates. Their cyclization by heating in sulfuric acid gave corresponding hydroxyquinolinones of excellent purity.
A novel and efficient method has been developed for the synthesis of highly functionalized benzo[g]- and dihydropyrano[2,3-g]chromene derivatives via addition and subsequently cyclization of 2-hydroxynaphthalene-1,4-dion...A novel and efficient method has been developed for the synthesis of highly functionalized benzo[g]- and dihydropyrano[2,3-g]chromene derivatives via addition and subsequently cyclization of 2-hydroxynaphthalene-1,4-dione or 2,5-dihydroxycyclohexa-2,5-diene-1,4-dione to the condensation product of an aldehyde with malononitrile in the presence of a catalytic amount of Et(3)N in CH(3)CN at ambient temperature. The procedures are very facile. The products can be obtained with simple filtration in high yields, and no more purification is needed. These compounds are closely related to ring systems such as beta-lapachone, alpha-xiloidone, lambertellin, pyranokunthone B, and WS-5995A, which have a broad spectrum of biological activities.
An efficient and green method for the synthesis of highly substituted cyclohexa-1,3-diene, polyhydroindene, polyhydronaphthalene, isochromene, isothiochromene, and isoquinoline derivatives has been developed. The synthes...An efficient and green method for the synthesis of highly substituted cyclohexa-1,3-diene, polyhydroindene, polyhydronaphthalene, isochromene, isothiochromene, and isoquinoline derivatives has been developed. The synthesis was achieved by using a multicomponent procedure in ionic liquid media. The features of this procedure are characterized by the following: mild reaction conditions, high yields, one-pot procedures, operational simplicity, and environmentally benign conditions.
To identify novel potentially broad spectrum antiviral compounds against RNA viruses, we have developed the parallel synthesis of a structurally interesting class of 2-substituted-4,5-dihydroxypyrimidine-6-carboxamides....To identify novel potentially broad spectrum antiviral compounds against RNA viruses, we have developed the parallel synthesis of a structurally interesting class of 2-substituted-4,5-dihydroxypyrimidine-6-carboxamides. Variously 2-substituted-4,5-dihydroxypyrimidine-6-carboxylate methyl esters were initially prepared and were then diversified via a facile amidation reaction. This strategy affords libraries of thousands of diverse drug-like compounds for screening. Biological evaluation of a set of these compounds, via a small initial screen, identified antiviral compounds against a representative RNA virus (Sendai virus, a paramyxovirus). We provide details on the synthetic protocols and the in vitro antiviral activity studies, as part of our initial investigation of the resulting targeted libraries.
With the goal of discovering a selective agonist of estrogen-related receptor gamma (ERRgamma) with enhanced potency, we designed a series of small-molecule ligands derived from a known ERRgamma agonist, GSK4716, that ca...With the goal of discovering a selective agonist of estrogen-related receptor gamma (ERRgamma) with enhanced potency, we designed a series of small-molecule ligands derived from a known ERRgamma agonist, GSK4716, that can substantially potentiate the transcriptional activity of ERRgamma. Individual compounds among a 30-member library of acyl hydrazones were pre-evaluated through in silico docking studies on the receptor cavities of ERRgamma LBDs using X-ray crystal structures cocrystallized with GSK4716 and 4-OHT. This rational approach to achieve the enhanced potency in ERRgamma transcriptional activity with selectivity over ERRalpha/beta enables us to complete the construction of a focused library by carrying out microwave-assisted parallel synthesis with excellent yields and purities. Finally, we identified a more potent ERRgamma agonist, E6, with excellent selectivity over ERRalpha/beta.
Two genetic algorithms for the single- and multiobjective design of combinatorial experiments were applied to the optimization of a solid catalyst system active in the selective catalytic oxidation of propane to propylen...Two genetic algorithms for the single- and multiobjective design of combinatorial experiments were applied to the optimization of a solid catalyst system active in the selective catalytic oxidation of propane to propylene. The two different optimization strategies, namely, the single objective optimization of the yield and the multiobjective optimization of the conversion and selectivity were implemented and compared. It was observed that the multiobjective approach optimized the yield in a similar way compared to the single objective approach. With respect to the selectivity, however, the multiobjective outperformed the single objective approach. It was also found that by applying the multiobjective optimization more interesting possible combinations were discovered.
3-Iodoindoles have been synthesized by the iodocyclization of N,N-dialkyl-o-(1-alkynyl)anilines, obtained by the Pd/Cu catalyzed coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines. These 3-iodoindoles underg...3-Iodoindoles have been synthesized by the iodocyclization of N,N-dialkyl-o-(1-alkynyl)anilines, obtained by the Pd/Cu catalyzed coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines. These 3-iodoindoles undergo palladium-catalyzed Sonogashira and Suzuki coupling reactions to yield 1,2,3-trisubstituted indoles. These reactions have been applied to parallel library synthesis utilizing commercially available terminal acetylenes and boronic acids. The aforementioned chemistry has also been carried out on a chlorinated Wang resin as a solid support, affording 1,2,3,5-tetrasubstituted indoles after cleavage from the support. A diverse 42-member library of highly substituted indoles has been synthesized.
The solution-phase synthesis of a 111 member isoquinoline library is described. The isoquinoline scaffold has been accessed through the palladium- and copper-catalyzed cyclization of iminoalkynes and the palladium-cataly...The solution-phase synthesis of a 111 member isoquinoline library is described. The isoquinoline scaffold has been accessed through the palladium- and copper-catalyzed cyclization of iminoalkynes and the palladium-catalyzed iminoannulation of internal alkynes, followed by diversification of hydroxyl functionality where it is present.
An efficient method to synthesize gem-difluorinated compounds on solid supports is described. The strategy is based on the design of a novel sulfur linker system that enables, to the best of our knowledge for the first t...An efficient method to synthesize gem-difluorinated compounds on solid supports is described. The strategy is based on the design of a novel sulfur linker system that enables, to the best of our knowledge for the first time, the release of target structures from the resin under simultaneous fluorination. Starting from an immobilized dithiol, coupling with an excess of aldehyde or ketone furnished dithianes. These can be further functionalized prior to release from the resin using our newly developed fluorinating cleavage conditions. Amide forming reactions, palladium-catalyzed reactions (Heck, Suzuki, and Sonogashira couplings), reductions, alkylations, and olefinations were successfully explored on the linker. The difluorinated target substances were obtained in modest to excellent yields and in high purities.
Three small compound biaryl libraries featuring a novel fluorinating cleavage strategy for preparation of a difluoromethyl group were assembled on solid supports. The average reaction yield per step was up to 96% in a sy...Three small compound biaryl libraries featuring a novel fluorinating cleavage strategy for preparation of a difluoromethyl group were assembled on solid supports. The average reaction yield per step was up to 96% in a synthetic sequence over five to six steps. Key features were Suzuki coupling reactions, transesterification with potassium cyanide and amidation reaction with trimethyl aluminum on solid supports.