Direct C-H Arylation as a Chemoselective Single-Step Access to π-Acceptor-π Type Building Blocks

2017 ◽  
Vol 359 (21) ◽  
pp. 3805-3817 ◽  
Author(s):  
Kuan-Ming Lu ◽  
Wei-Ming Li ◽  
Po-Yu Lin ◽  
Kuan-Ting Liu ◽  
Ching-Yuan Liu
Keyword(s):  
Building Blocks ◽  
Single Step

scholarly journals Synthetically Accessible Virtual Inventory (SAVI)

2020 ◽  
Author(s):  
Hitesh Patel ◽  
Wolf Ihlenfeldt ◽  
Philip Judson ◽  
Yurii S. Moroz ◽  
Yuri Pevzner ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Chemical Synthesis ◽  
Programming Languages ◽  
Expert Knowledge ◽  
Scoring Systems ◽  
Building Blocks ◽  
Single Step

We have made available a database of over 1 billion compounds predicted to be easily synthesizable. They have been created by a set of transforms based on an adaptation and extension of the CHMTRN/PATRAN programming languages describing chemical synthesis expert knowledge, which originally stem from the LHASA project. The chemoinformatics toolkit CACTVS was used to apply a total of 53 transforms to about 150,000 readily available building blocks (enamine.net). Only single-step, two-reactant syntheses were calculated for this database even though the technology can execute multi-step reactions. The possibility to incorporate scoring systems in CHMTRN allowed us to subdivide the database of 1.75 billion compounds in sets according to their predicted synthesizability, with the most-synthesizable class comprising 1.09 billion synthetic products. Properties calculated for all SAVI products show that the database should be well-suited for drug discovery. It is being made publicly available for free download from https://cactus.nci.nih.gov/download/savi_download/.

Bifunctional hybrid catalysts derived from Cu/Zn-based nanoparticles for single-step dimethyl ether synthesis

2016 ◽  
Vol 6 (4) ◽  
pp. 1054-1063 ◽  
Author(s):  
M. Gentzen ◽  
W. Habicht ◽  
D. E. Doronkin ◽  
J.-D. Grunwaldt ◽  
J. Sauer ◽  
...  
Keyword(s):  
Dimethyl Ether ◽  
Building Blocks ◽  
Single Step ◽  
Bifunctional Catalysts ◽  
Hybrid Catalysts ◽  
Dimethyl Ether Synthesis ◽  
Ether Synthesis

Model kit for bifunctional catalysts: colloidal Cu/Zn-based nanoparticles were synthesized and used as building blocks in syngas to dimethyl ether (STD) catalysts.

scholarly journals Cobalt Hydride Oxidase Catalysis Enabled Hydroamination of Unactivated Olefins

2021 ◽  
Author(s):  
Wei-Ting Ye ◽  
Rong Zhu
Keyword(s):  
Building Blocks ◽  
Single Step ◽  
Tertiary Amines ◽  
Mechanistic Studies ◽  
Organic Transformations ◽  
Design Elements ◽  
Alkyl Radicals ◽  
Solvent Free Conditions ◽  
Oxidative Processes ◽  
Nitrogen Nucleophiles

Dioxygen is an abundant, selective, and sustainable oxidant that is considered ideal for organic transformations. Oxidative processes using dioxygen as the electron acceptor without oxygen atom incorporation into the substrate are often referred to as oxidase reactions. However, the ground state triplet nature of dioxygen makes such a synthetically valuable pathway incompatible with simple free alkyl radicals, a ubiquitous class of reactive intermediates in the daily synthesis of pharmaceuticals, agrochemicals, and complex natural products. Here we report that a combination of strong cage effect and bimetallic radical-polar crossover successfully addresses this problem, and opens up an oxidase pathway in cobalt hydride catalysis. This leads to a general and chemoselective method that tackles several key challenges in catalytic hydroamination, a fundamental transformation for amine synthesis. Under balloon pressure of dioxygen at ambient temperature, we demonstrate single-step intra- and intermolecular formal addition of a variety of nitrogen nucleophiles, including free amines, sulfonamides, amides, and carbamates, to unactivated alkenes in the presence of a silane, under solvent-free conditions. Important medicinal chemistry building blocks such as a-branched tertiary amines can be easily accessed, which are often difficult targets otherwise due to their steric hindrance and reducing nature. Mechanistic studies including stoichiometric experiments with well-defined organocobalt complexes provide support for the key hypothesis, which points the way to the development of sustainable processes involving other nucleophiles based on the same design elements.

scholarly journals Engineered Biosynthesis of β-Alkyl Tryptophan Analogs

2018 ◽  
Author(s):  
Christina E. Boville ◽  
Remkes A. Scheele ◽  
Philipp Koch ◽  
Sabine Brinkmann-Chen ◽  
Andrew R. Buller ◽  
...  
Keyword(s):  
Pyrococcus Furiosus ◽  
Building Blocks ◽  
Single Step ◽  
Environmentally Benign ◽  
Tryptophan Synthase ◽  
X Ray Crystallography ◽  
Potential Applications ◽  
Uv Visible ◽  
Substrate Tolerance ◽  
Multi Step Methods

<a>Non-canonical amino acids (ncAAs) with dual stereocenters at the α and β positions are valuable precursors to natural products and therapeutics. Despite the potential applications of such bioactive β-branched ncAAs, their availability is limited due to the inefficiency of the multi-step methods used to prepare them. Here we report a stereoselective biocatalytic synthesis of β-branched tryptophan analogs using an engineered variant of <i>Pyrococcus furiosus</i> tryptophan synthase (<i>Pf</i>TrpB), <i>Pf</i>TrpB<sup>7E6</sup>. <i>Pf</i>TrpB<sup>7E6</sup> is the first biocatalyst to synthesize bulky β-branched tryptophan analogs in a single step, with demonstrated access to 27 ncAAs. The molecular basis for the efficient catalysis and broad substrate tolerance of <i>Pf</i>TrpB<sup>7E6</sup> was explored through X-ray crystallography and UV-visible light spectroscopy, which revealed that a combination of active-site and remote mutations increase the abundance and persistence of a key reactive intermediate. <i>Pf</i>TrpB<sup>7E6</sup> provides an operationally simple and environmentally benign platform for preparation of β-branched tryptophan building blocks.</a>

Enantioselective aliphatic C–H bond oxidation catalyzed by bioinspired complexes

2018 ◽  
Vol 54 (69) ◽  
pp. 9559-9570 ◽  
Author(s):  
Michela Milan ◽  
Massimo Bietti ◽  
Miquel Costas
Keyword(s):  
Organic Synthesis ◽  
Building Blocks ◽  
Single Step

Enantioselective aliphatic C–H bond oxidation simultaneously installs functionality and chirality into hydrocarbon units, converting in a single step readily available, inexpensive and typically inert hydrocarbons into precious building blocks for organic synthesis.

scholarly journals Propane to olefins tandem catalysis: a selective route towards light olefins production

2021 ◽  
Author(s):  
Matteo Monai ◽  
Marianna Gambino ◽  
Sippakorn Wannakao ◽  
Bert M. Weckhuysen
Keyword(s):  
Chemical Industry ◽  
Building Blocks ◽  
Single Step ◽  
Propane Dehydrogenation ◽  
Light Olefins ◽  
Tandem Catalysis ◽  
Challenges And Opportunities ◽  
Propylene Metathesis

Combining propane dehydrogenation with propylene metathesis in a single step yields mixtures of propylene, ethylene and butenes, important building blocks for the chemical industry. The open challenges and opportunities in the field are highlighted.

scholarly journals The influence of silica nanoparticles on thermal degradation and mechanical properties of nanocomposites based on aliphatic polyurethanes

2018 ◽  
Vol 72 (4) ◽  
pp. 215-227
Author(s):  
Jelena Pavlicevic ◽  
Milena Spirková ◽  
Oskar Bera ◽  
Mirjana Jovicic ◽  
Dejan Kojic ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Silica Nanoparticles ◽  
Degradation Mechanism ◽  
Building Blocks ◽  
Silica Content ◽  
Single Step ◽  
Onset Temperature

Nanocomposites based on aliphatic polyurethanes have recently attracted a lot of attention regarding economical and ecological aspects, due to their improved thermal and mechanical properties. The aim of this paper was to investigate the influence of silica nanoparticles, differing in size and specific surface, on thermal stability and degradation, lifetime and mechanical characteristics of the obtained nanocomposites. Two series of nanocomposites based on aliphatic polyurethanes were obtained by using a single-step procedure and by addition of silica nanoparticles of types A380 or N999 at different loadings (0,0 0.15, 0.5, 1,0 and 3.5 wt.%). It was found that the increase in heating rate caused shifting of the onset temperature to higher values (from 283 to 312 ?C). According to the shape of DTG curves, it was observed that the degradation mechanism of prepared nanocomposites consists of two overlapping processes, related to the scission of hard and soft building blocks. Based on DTG results, the addition of larger N999 silica nanoparticles induced lower thermal degradation, shifting the maximum rate temperatures of the first and second degradation stages to lower values, and caused the change in the degradation mechanism. Addition of smaller silica nanoparticles (A380) did not significantly affect the mechanism of the degradation reaction, indicating homogeneity of the obtained nanocomposites. The presence of A380 nanoparticles improved thermal stability of nanocomposites, by increasing the onset temperature from 286 ?C for the pristine elastomer to 303 ?C for the sample containing 3.5 wt.% of silica. Existence of interactions of A380 silica nanoparticles with hard and soft phases was observed, based on the increase in the maximum rates of the first and second degradation steps. The activation energy of thermal degradation of polyurethanes modified with A380 silica nanoparticles was obtained by using the Flyn-Wall and Toop models. Dependence of the activation energy and the lifetime of nanocomposites based on aliphatic polyurethanes on the silica content were estimated. The highest Ea values (determined for 1 and 5 % weight loss) were found for nanocomposites containing 0.5 and 0.15 wt. % of A380 silica nanoparticles (121 and 161.2 kJ/mol). A negative effect of the silica addition on mechanical properties of nanocomposites was observed. The polyurethanes containing smaller SiO2 particles (A380) had a higher tensile strength, elongation at break and hardness as compared to the elastomers filled with larger silica nanoparticles (N999).

Synthesis, Thermal Properties and Crystal Structure of Twinned Crystals of the New Coordination Polymer Poly[(CuBr)2(μ2-pyrimidine-N,N’)]

2003 ◽  
Vol 58 (11) ◽  
pp. 1105-1111 ◽  
Author(s):  
Christian Näther ◽  
Inke Jeß ◽  
Michael Bolte
Keyword(s):  
Crystal Structure ◽  
Coordination Polymer ◽  
Bromine Atom ◽  
Exothermic Reaction ◽  
Building Blocks ◽  
Single Step ◽  
Donor Ligands ◽  
Structure Model ◽  
Twin Domain ◽  
Second Twin

Abstract Reaction of copper(I) bromide with pyrimidine in acetonitrile leads to the formation of crystals of the new coordination polymer poly[(CuBr)2(μ2-pyrimidine-N,N’)]. Indexing of the reflections yields a monoclinic primitive cell with a = 3.9119(2), b = 13.525(1), c = 15.346(1)Å , β = 97.29(1)° and V =805.4(1) Å3. Inspection of the reciprocal space shows weak reflections which might be indicative of a superstructure leading to a doubling of the crystallographic c-axis. The structure can be solved in space group P21/m but the refinement leads to very poor reliability factors (wR2 for all refl.: 62.57%, R1 for all Fo > 4σ (Fo) = 27.84%). A twin refinement assuming merohedral twinning drastically reduces the R-values (wR2 for all refl.: 7.27%, R1 for all Fo > 4σ (Fo) = 2.64%) and a structure model is obtained which consists of two crystallographically independent copper and bromine atoms and two pyrimidine ligands in the asymmetric unit. However, carefull inspection of this structure shows that the two crystallographically independent layers formed by the connection of the building blocks are very similar and that they are related by a translation by half of the crystallographic c-axis. As a result of that, the crystal is just a partial merohedral twin and the reflections which led to the assumption that the c-axis is twice as long are generated by the second twin domain. The structure was refined with the correct twin law (wR2 for all refl.: 6.70%, R1 for all Fo > 4σ (Fo) = 2.57%). By this procedure a reasonable structure model is obtained which consists of one crystallographically independent copper and bromine atom and one pyrimidine ligand. In the crystal structure CuBr double chains are formed which are connected into layers via μ-N,N’ coordination by the N-donor ligands. On heating, the compound loses all of the ligands and transforms into CuBr within only one single step in an exothermic reaction.

Sign in / Sign up

Export Citation Format

Share Document