Warning: Constant WP_CRON_LOCK_TIMEOUT already defined in /htdocs/wp-config.php on line 91
Non classé – ChemDigest

Non classé

Synthesis and Structure–Activity Relationship Studies of C(13)‐Desmethylene‐(−)‐Zampanolide Analogs

Par / 30 mai 2023 / Non classé
Synthesis and Structure–Activity Relationship Studies of C(13)-Desmethylene-(−)-Zampanolide Analogs

The sponge-derived, highly unsaturated marine macrolide (−)-zampanolide is a potent antimitotic agent and cancer cell growth inhibitor. By using a convergent synthetic approach, the shown series of partially reduced and/or demethylated analogs were obtained. Depending on the site of modification, these compounds show a range of microtubule-binding affinities and cellular activities, thus providing new insights into the relative importance of specific double bonds and methyl groups for biological activity. More information can be found in the Research Article by K.-H. Altmann and co-workers (DOI: 10.1002/chem.202300703).

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Tobias M. Brütsch, Etienne Cotter, Daniel Lucena‐Agell, Mariano Redondo‐Horcajo, Carolina Davies, Bernhard Pfeiffer, Sandro Pagani, Simone Berardozzi, J. Fernando Díaz, John H. Miller, Karl‐Heinz Altmann
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202301652

Antitumor Activity and Reductive Stress by Platinum(II) N‐Heterocyclic Carbenes based on Guanosine

Par / 30 mai 2023 / Non classé
Antitumor Activity and Reductive Stress by Platinum(II) N-Heterocyclic Carbenes based on Guanosine**

Platinum(II) complexes bearing NHCs based on guanosine undergo a substantial increase in antiproliferative activity when changing the ligand trans to the NHC from bromide to hydride. Compound 6 leads to an increase in reductive stress and increase in glutathione levels in cancer cells but not in non-cancer cells.

Abstract

Platinum(II) complexes bearing N-heterocyclic carbenes based guanosine and caffeine have been synthesized by unassisted C−H oxidative addition, leading to the corresponding trans-hydride complexes. Platinum guanosine derivatives bearing triflate as counterion or bromide instead of hydride as co-ligand were also synthesized to facilitate correlation between structure and activity. The hydride compounds show high antiproliferative activity against all cell lines (TC-71, MV-4-11, U-937 and A-172). Methyl Guanosine complex 3, bearing a hydride ligand, is up to 30 times more active than compound 4, with a bromide in the same position. Changing the counterion has no significant effect in antiproliferative activity. Increasing bulkiness at N7, with an isopropyl group (compound 6), allows to maintain the antiproliferative activity while decreasing toxicity for non-cancer cells. Compound 6 leads to an increase in endoplasmic reticulum and autophagy markers on TC71 and MV-4-11 cancer cells, induces reductive stress and increases glutathione levels in cancer cells but not in non-cancer cell line HEK-293.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Maria Inês P. S. Leitão, Maria Turos‐Cabal, Ana Maria Sanchez‐Sanchez, Clara S. B. Gomes, Federico Herrera, Vanesa Martin, Ana Petronilho
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202301078

Pnictogen Interactions with Nitrogen Acceptors

Par / 30 mai 2023 / Non classé
Pnictogen Interactions with Nitrogen Acceptors

Molecular rotors were designed to experimentally measure the transition state stabilizing abilities of nitrogen pnictogen interactions. The rotors formed intramolecular C=O⋅⋅⋅N interactions in the bond rotation transition states. Many common nitrogen functional groups were observed to form stabilizing interactions including amides, imines, and nitro groups.

Abstract

Stabilizing nitrogen pnictogen bond interactions were measured using molecular rotors. Intramolecular C=O⋅⋅⋅N interactions were formed in the bond rotation transition states which lowered the rotational barriers and increased the rates of rotation, as measured by EXSY NMR. The pnictogen interaction energies show a very strong correlation with the positive electrostatic potential on nitrogen, which was consistent with a strong electrostatic component. In contrast, the NBO perturbation and pyramidalization analyses show no correlation, suggesting that the orbital-orbital component is minor. The strongest C=O⋅⋅⋅N pnictogen interactions were comparable to C=O⋅⋅⋅C=O interactions and were stronger than C=O⋅⋅⋅Ph interactions, when measured using the same N-phenylimide rotor system. The ability of the nitrogen pnictogen interactions to stabilize transition states and enhance kinetic processes demonstrates their potential in catalysis and reaction design.

Wiley: Angewandte Chemie International Edition: Table of Contents
Authors: Binzhou Lin, Hao Liu, Ishwor Karki, Erik C. Vik, Mark D. Smith, Perry J. Pellechia, Ken D. Shimizu
onlinelibrary.wiley.com/doi/10.1002/anie.202304960

Wavy Graphene-Like Network Forming during Pyrolysis of Polyacrylonitrile into Carbon Fiber

Par / 30 mai 2023 / Non classé

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Toru Ishikawa, Fumihiko Tanaka, Kosuke Kurushima, Akira Yasuhara, Ryusuke Sagawa, Tatsuya Fujita, Ryohei Yonesaki, Katsuhiko Iseki, Takayuki Nakamuro, Koji Harano, and Eiichi Nakamura
dx.doi.org/https://doi.org/10.1021/jacs.3c02504

Synergy of Single Atoms and Lewis Acid Sites for Efficient and Selective Lignin Disassembly into Monolignol Derivatives

Par / 30 mai 2023 / Non classé

TOC Graphic

Journal of the American Chemical Society

Journal of the American Chemical Society: Latest Articles (ACS Publications)
Authors: Ge Meng, Wu Lan, Lilong Zhang, Shibin Wang, Tanhao Zhang, Shuo Zhang, Ming Xu, Yu Wang, Jian Zhang, Fengxia Yue, Yulong Wu, and Dingsheng Wang
dx.doi.org/https://doi.org/10.1021/jacs.3c04028

Approaches and Considerations for the Investigation and Synthesis of N‑Nitrosamine Drug Substance-Related Impurities (NDSRIs)

Par / 30 mai 2023 / Non classé

TOC Graphic

Organic Process Research & Development
Organic Process Research & Development: Latest Articles (ACS Publications)

Authors: Ian W. Ashworth, Alexander Blanazs, Jonathan J. Byrne, Olivier Dirat, Jared W. Fennell, Nadine Kuhl, Stuart L. Wells, and Matthew P. Whiting
dx.doi.org/https://doi.org/10.1021/acs.oprd.3c00084

N‐Boc‐Protected α‐Amino Acids by 1,3‐Migratory Nitrene C(sp3)−H Insertion

Par / 26 mai 2023 / Non classé
N-Boc-Protected α-Amino Acids by 1,3-Migratory Nitrene C(sp3)−H Insertion

A straightforward two-step protocol was developed to convert linear or α-branched carboxylic acids into non-racemic N-Boc-protected α-monosubstituted (asymmetric catalysis) or α,α-disubstituted (enantioconvergent catalysis) α-amino acids.

Abstract

N-Boc-protected α-amino acids are synthesized in two steps from linear or branched carboxylic acid feedstocks. In the first step, the carboxylic acid is coupled with tert-butyl aminocarbonate (BocNHOH) to generate azanyl ester (acyloxycarbamate) RCO2NHBoc. In the second step, this azanyl ester undergoes a stereocontrolled iron-catalyzed 1,3-nitrogen migration to generate the N-Boc-protected non-racemic α-amino acid. This straightforward protocol is applicable to the catalytic asymmetric synthesis of α-monosubstituted α-amino acids with aryl, alkenyl, and alkyl side chains. Furthermore, α,α-disubstituted α-amino acids are accessible in an enantioconvergent fashion from racemic carboxylic acids. The new method is also advantageous for the synthesis of α-deuterated α-amino acids. N-Boc-protected α-amino acids synthesized using this two-step protocol are ready-to-use building blocks.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Bing Zhou, Chen‐Xi Ye, Eric Meggers
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202300296

CO2‐Enhanced Production and Synthesis of 2,5‐ Furandicarboxylic Acid under CO2 Flow through Henkel Reaction

Par / 26 mai 2023 / Non classé
CO2-Enhanced Production and Synthesis of 2,5- Furandicarboxylic Acid under CO2 Flow through Henkel Reaction

The pathways and rate-determining steps of the preparation of 2,5-furandicarboxylic acid are identified. The approach includes CO2 flow via the Henkel reaction. The improvements include the mild operating conditions such as atmospheric condition and highest yield among the literatures.

Abstract

The present study investigated the preparation of 2,5-furandicarboxylic acid (FDCA) via the Henkel reaction between furoic acid alkali metal salts and zinc chloride under a continuous CO2 flow at atmospheric pressure. The results obtained were compared with those of previous studies that used high-pressure conditions or toxic cadmium catalysts. The pathways and rate-determining steps of the reaction are revealed for the first time. Furthermore, the enhanced formation of FDCA through the promotion of carboxyl exchange and rearrangement during the reaction under a CO2 flow was examined. The CO2-rich environment afforded a high FDCA yield of 86.30 %, which is the highest yield obtained to date using the Henkel reaction. The findings of this study offer economically improved conditions for large-scale FDCA production.

Wiley: European Journal of Organic Chemistry: Table of Contents
Authors: Po‐Hsun Chang, David Shan‐Hill Wong, John Di‐Yi Ou, Yung‐Tin Pan, Shi‐Shang Jang
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ejoc.202300396

Hydrogen Bonding Parameters by Rapid Colorimetric Assessment: Evaluation of Structural Components Found in Biological Ligands and Organocatalysts

Par / 26 mai 2023 / Non classé
Hydrogen Bonding Parameters by Rapid Colorimetric Assessment: Evaluation of Structural Components Found in Biological Ligands and Organocatalysts

A high throughput UV-Vis method to measure hydrogen bonding capacity is disclosed using over 100 compounds of biological and catalytic relevance. A multiple linear regression model enables estimation of hydrogen bonding affinity from a single measurement using ∼2 mg of analyte that was showcased with a set of carboxylic acid bioisosteres.

Abstract

Hydrogen bonding is a key molecular interaction in biological processes, drug delivery, and catalysis. This report describes a high throughput UV-Vis spectroscopic method to measure hydrogen bonding capacity using a pyrazinone sensor. This colormetric sensor reversibly binds to a hydrogen bond donor, resulting in a blue shift as additional equivalents of donor are added. Titration with excess equivalents of donor is used to determine the binding coefficient, ln(Keq). Over 100 titrations were performed for a variety of biologically relevant compounds. This data enabled development a multiple linear regression model that is capable of predicting 95 % of ln(Keq) values within 1 unit, allowing for the estimation of hydrogen bonding affinity from a single measurement. To show the effectiveness of the single point measurements, hydrogen bond strengths were obtained for a set of carboxylic acid bioisosteres. The values from the single point measurements were validated with full titrations.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Hanna F. Roenfanz, Thomas J. Paniak, Cameron B. Berlin, Van Tran, Karol R. Francisco, Pierrik Lassalas, Anisha Devas, Olivia Landes, Avalon Rosenberger, Madeline E. Rotella, Carlo Ballatore, Marisa C. Kozlowski
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202300696

Late‐Stage Functionalization for the Divergent Synthesis of Podophyllotoxin Derivatives by Rhodium Catalysis

Par / 26 mai 2023 / Non classé
Late-Stage Functionalization for the Divergent Synthesis of Podophyllotoxin Derivatives by Rhodium Catalysis

Divergent synthesis of novel podophyllotoxin derivatives from available starting materials by late-stage functionalization strategy by rhodium catalysis is described. Exquisite selectivity for podophyllotoxin functionalization was demonstrated through arylation, alkenylation and cyclization at C5 position.

Abstract

A divergent synthesis of podophyllotoxin derivatives from simple and readily available starting materials through a late-stage functionalization strategy by rhodium catalysis is reported here. This strategy uses the ketone and oxime in substrates as directing groups. Four kinds of novel podophyllotoxin derivatives have been obtained without any erosion of the enantiopurity, thus indicating the broad substrate scope of this method. Additionally, by using the newly developed strategy, 9 aa, which exhibited excellent anticancer activity, can be prepared by a sequential transformation. In particularly, 9 aa suppressed HeLa cells with IC50 values of 74.5 nM, thus providing a promising lead compound for future drug discovery.

Wiley: Chemistry – A European Journal: Table of Contents
Authors: Yue Zhao, Yangpeng Shen, Jian He, Jing Li, Shengbin Zhou, Yunbo Wang, Chunpu Li, Hong Liu
chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202300960