Article
Chemistry, Multidisciplinary
Jun-Jie Yin, Yun-Peng Wang, Jun Xue, Feng-Fan Zhou, Xing-Qian Shan, Rong Zhu, Kun Fang, Lei Shi, Shu-Yu Zhang, Si-Hua Hou, Wujiong Xia, Yong-Qiang Tu
Summary: The first total syntheses of polycyclic diterpenes phomopsene (1), methyl phomopsenonate (2), and iso-phomopsene (3) have been achieved through an unusual cascade reorganization of C-C single bonds. This approach involves a synergistic Nazarov cyclization/double ring expansion for rapid and stereospecific construction of the tetraquinane scaffold, as well as a one-pot strategic ring expansion through Beckmann fragmentation/recombination to efficiently assemble the tetracyclic skeleton. The correct structure of iso-phomopsene was determined to be the C7 epimer of the originally assigned structure, and the absolute configurations of the target molecules were confirmed through enantioselective synthesis.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Jiuyu Liu, Jiechun Tang, Jiaxu Chen, Tingjie Ge, Xingyi Zhao, Jundong Xu, Ping Gong, Yunlei Hou
Summary: This paper presents an efficient synthesis method for substituted (Z)-N-allyl sulfonamides via a three-component tandem reaction catalyzed by Pd(PPh3)4. The optimal catalyst, base, and solvent used were 2.5 mol % Pd(PPh3)4, K2CO3, and THF, respectively. The desired products were obtained in an overall yield of 30-83%. Mechanistic investigations showed that the control of the formation of the single (Z)-isomer relied on the formation of a six-membered palladacycle intermediate.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Seoyeon Kim, Yunjeong Lee, Eun Jin Cho
Summary: In this study, a visible-light-induced selective homocoupling reaction of propargyl bromides to form 1,5-diynes was developed. The key step in the reaction involves the generation of propargyl radicals through a reductive quenching cycle of the photoexcited [Ir(III)]* photocatalyst. The formed 1,5-diyne can be further converted to functionalized indole derivatives through coupling reactions.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Biochemistry & Molecular Biology
Itaru Nakamura, Mai Tachibana, Riku Konta, Hiroki Tashiro, Masahiro Terada
Summary: Cu-catalyzed reactions of N-alkoxy-2-methylanilines and alcohols in the presence of IPrCuBr and AgSbF6 afford meta-aminophenol derivatives through a [1,3]-rearrangement and an oxa-Michael reaction.
Review
Crystallography
Weiqing She, Zhenzhen Xu, Lianjie Zhai, Junlin Zhang, Jie Huang, Weiqiang Pang, Bozhou Wang
Summary: Due to the introduction of oxygen atoms, N-oxide energetic compounds possess unique advantages in terms of oxygen balance, detonation properties, and energy density, which have attracted extensive attention from researchers worldwide. This article provides a comprehensive review of the synthetic strategies for two categories of N-oxides, azine N-oxides and azole N-oxides, and discusses the reaction mechanisms of aromatic N-oxide frameworks and their applications in creating high-energy substances. Furthermore, the energetic properties of N-oxide energetic compounds are compared and summarized.
Article
Chemistry, Multidisciplinary
Chenlong Zhu, Thomas R. Hoye
Summary: In this report, a new variant of the HDDA process is revealed, which reduces the activation barrier for the reaction by introducing a central quaternized nitrogen atom. Furthermore, the cyclization of substrates can be achieved spontaneously at room temperature.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Li Chen, Jin-Mei Qi, Shu Yang, Si-Nuo Sun, Sheng-Jiao Yan
Summary: We have developed a new method to synthesize functionalized chromeno[2,3-c]pyrrol-9(1H)-one derivatives (CMPOs) 3 and 3' from 3-formylchromones by reacting with proline derivatives. This strategy involves a cascade reaction that occurs by simply heating a mixture of substrates 1 with 2 and toluene, followed by oxidation with oxygen and catalysis by CuBr. In a single step, this protocol cleaves two bonds (2 C-C) and forms three bonds (1 C-N and 2 C-C bonds) to produce a range of CMPOs 3 and 3'. This method can be used to synthesize functionalized CMPOs for combinatorial and parallel syntheses in a one-pot reaction.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Biochemistry & Molecular Biology
Saman Sayebani, Hossein Eshghi, Maryam Naeimabadi
Summary: A new and diverse route has been developed for synthesis of novel pyrrole derivatives using azomethine ylides. The azomethine ylides are produced via C-H activation and then reacted with olefins to form pyrrole derivatives. This synthetic method shows moderate to excellent yields in experiments.
MOLECULAR DIVERSITY
(2022)
Article
Chemistry, Organic
Lei Huang, Yan Wang, Xin Liu, Shi-Kai Tian
Summary: This study presents a method for synthesizing thiolated 2,7-disubstituted tropones via the reaction between 2,4-dialkylidenetropinone-derived quaternary ammonium salts and thiols. The reaction proceeds smoothly with high selectivity, providing structurally diverse products. The method is practical, as it uses readily available starting materials and reagents and can be easily scaled up.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Fernando Murillo, Alan Quintal, Eugenia Dzib, Ximena Zarate, Maria A. Fernandez-Herrera, Gabriel Merino
Summary: By using quantum chemical computations, the most viable pathway for the synthesis of diarylamines was confirmed to be the 3-exo-trig Smiles rearrangement. It was also found that the substituents on the S-aryl ring can drastically affect the rearrangement barriers, while temperature rise favors the rearrangement reactions.
JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
(2022)
Review
Biochemistry & Molecular Biology
Boriss Strumfs, Kirils Velikijs, Romans Uljanovs, Stanislavs Sinkarevs, Ilze Strumfa
Summary: This review mainly focuses on recently described or updated ways to obtain 3-arylated aziridines via different non-aziridination-based synthetic methods. These methods primarily include cyclization of open-chain substrates and rearrangement of other heterocycles.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Chemistry, Organic
Alexander Sandvoss, Johannes M. Wahl
Summary: A variety of cyclic alcohols can be converted into medicinally relevant heterocycles by subjecting them to nitrogen insertion using O-mesitylsulfonylhydroxylamine. The use of fluorinated alcoholic solvents is crucial to activate the substrates and allow them to react with the ambiphilic aminating agent. This transition-metal-free reaction also provides an unprecedented access to indoles from ortho-substituted acetophenones when combined with a photochemical Norrish-Yang-type cyclization.
Article
Chemistry, Organic
Tsubasa Hino, Noriki Kutsumura, Tsuyoshi Saitoh, Naoshi Yamamoto, Yasuyuki Nagumo, Yuzo Mogi, Yoshikazu Watanabe, Hiroshi Nagase
Summary: A novel molecular oxygen-mediated Baeyer-Villiger-type oxidation specific to the morphinan skeleton has been discovered, yielding unexpected cyclopropanecarboxylic acid and ketolactone derivatives. The reactive sites in those products are oriented over the C-ring in the morphinan skeleton, making them useful intermediates for designing ideal kappa opioid receptor agonists.
TETRAHEDRON LETTERS
(2021)
Article
Chemistry, Organic
Tanawat Phumjan, Poramate Songthammawat, Jira Jongcharoenkamol, Paratchata Batsomboon, Somsak Ruchirawat, Poonsakdi Ploypradith
Summary: Starting from benzaldehyde derivatives, 9-anthraldehydes were prepared in good yields through a series of steps involving epoxidation and acid-catalyzed processes. Factors affecting the yield included the nature of the alcohol substrate and substituents on the aromatic ring. Mechanistic studies revealed that the semipinacol rearrangement of the epoxide is a crucial step in the formation of 9-anthraldehydes.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Xi Feng, Zhen Qin, Xinying Cheng, Dongyu Liu, Yinghe Peng, Huidan Huang, Bin Song, Jinlei Bian, Zhiyu Li
Summary: An efficient protocol for synthesizing furo[3,2-c]coumarin derivatives is described in this study, which resulted in good to excellent yields of the desired furocoumarins. Large-scale substrate screening and preparation were conducted, along with evaluation of photophysical properties of selected compounds.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Izabel C. Medeiros-Costa, Eddy Dib, Florent Dubray, Simona Moldovan, Jean-Pierre Gilson, Jean-Pierre Dath, Nikolai Nesterenko, Hristiyan A. Aleksandrov, Georgi N. Vayssilov, Svetlana Mintova
Summary: This study reports a method for preparing defect-free MFI crystals containing single-site framework Mo. Through extensive spectroscopic characterization and experimental analysis, the insertion of single Mo sites in MFI zeolite samples with different crystal sizes was investigated, as well as the role of silanol groups in the incorporation of Mo into the zeolite structure.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Oriol Pique, Iskra Z. Koleva, Albert Bruix, Francesc Vines, Hristiyan A. . Aleksandrov, Georgi N. Vayssilov, Francesc Illas
Summary: In this study, the interaction between carbon and transition metal surfaces was investigated using density functional calculations. A holistic navigation map of these interactions was developed, with the d-band center identified as the most suitable descriptor. Additionally, both adsorption energies and the energy difference between minima were found to be appropriate descriptors for diffusion barriers. The combination of different descriptors improved the description of both thermodynamic and kinetic data.
Article
Biochemistry & Molecular Biology
Kristina B. Simeonova, Ana Koleva, Anna-Mariya R. Zlatanova, Nevena Petkova-Yankova, Hristiyan A. Aleksandrov, Petko St Petkov, Rositca D. Nikolova
Summary: The homodimerization process of 3-acetylcoumarin was achieved under sonication using a combination of zinc and metallic salt. Appropriate frequency and sound amplitude were identified as significant variables for the reaction initiation. Theoretical results suggested that the radical mechanism is more favorable, and the solvent plays an activating role on the reactivity of the Zn-salt.
Article
Biochemistry & Molecular Biology
Rumen Lyapchev, Ana Koleva, Iskra Z. Koleva, Kristian Subev, Ivelina Madzharova, Kristina B. Simeonova, Nevena Petkova-Yankova, Bernd Morgenstern, Vesela Lozanova, Petar Y. Petrov, Rositca D. Nikolova
Summary: Quantum-chemical calculations and experimental synthesis were used to obtain aryl substituted 3-phosphonocoumarins with promising fluorescent properties. The study found that the optical properties of phosphorous-containing coumarin systems can be fine-tuned by altering the substituent at C-6 position.
Article
Chemistry, Physical
Eddy Dib, Svetlana Mintova, Georgi N. Vayssilov, Hristiyan A. Aleksandrov, Marina Carravetta
Summary: By using a combination of symmetry-based recoupling in 29Si NMR, spin dynamics-based simulations, and DFT-based theoretical calculations, we demonstrate how to characterize the 29Si NMR peaks of (Si-O-Si), Bronsted acid sites (Si-OH-Al), and silanols (Si-OH) in nanosized ZSM-5 zeolites. Theoretical calculations and experimental observations reveal significant differences in the chemical shift anisotropy for silicon nuclei close to aluminum (Q(4)(1Al)) compared to those which are not, allowing for clear assignment of Si-29 NMR peaks. The isotropic chemical shift alone cannot differentiate these differences.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Nikola L. Drenchev, Elena Z. Ivanova, Mihail Y. Mihaylov, Hristiyan A. Aleksandrov, Georgi N. Vayssilov, Konstantin I. Hadjiivanov
Summary: To design efficient CO2 capture materials, it is important to ensure a high adsorption capacity. We have recently discovered that one Na+ site in NaY zeolite can attach two CO2 molecules, but the process occurs at a low temperature and is not suitable for practical use. We have now found that one Ca2+ site in CaNaY zeolite can attach three CO2 molecules, making it a promising material for CO2 capture.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Dong Gun Oh, Hristiyan A. Aleksandrov, Haneul Kim, Iskra Z. Koleva, Konstantin Khivantsev, Georgi N. Vayssilov, Ja Hun Kwak
Summary: In this study, it was demonstrated that the formation of PdOx on the surface plays a crucial role in the CH4 oxidation reaction of Pd-based catalysts, and the presence of PdO layer improves the catalytic activity. Density functional theory calculations helped elucidate the active site structures of Pd and PdO, providing insights for the design of active and durable Pd-based catalysts.
Article
Chemistry, Organic
Nevena I. I. Petkova-Yankova, Rositca D. D. Nikolova
Summary: Enol phosphates were synthesized from 3-diethylphosphonocoumarin under phase-transfer conditions, serving as modified conditions for tandem hydrogenation/phosphorylation reactions. The optimized reaction conditions exhibited high regioselectivity for O-phosphorylation and O-acylation. The newly synthesized enol phosphates were fully characterized by NMR spectroscopic techniques and were determined to be single (Z)-isomers.
SYNTHETIC COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Iskra Z. Koleva, Hristiyan A. Aleksandrov, Georgi N. Vayssilov
Summary: The mechanism of CO oxidation on platinum species supported on ceria or alumina was investigated using periodic density functional calculations. Various reaction paths involving different oxidation states of monoatomic species and platinum clusters were modeled to identify the catalytically active species. The calculations revealed that the reaction paths via Pt2+ and Pt4+ cations had the lowest activation barriers, while those involving Ce4+ cations had significantly higher barriers. The results provide insights into the role of oxidants in CO oxidation on platinum species supported on ceria or alumina.
Article
Chemistry, Multidisciplinary
Edwin B. Clatworthy, Simona Moldovan, Kalthoum Nakouri, Stoyan P. Gramatikov, Francesco Dalena, Marco Daturi, Petko St. Petkov, Georgi N. Vayssilov, Svetlana Mintova
Summary: This study directly visualizes the structural flexibility of a high-aluminum nano-sized RHO zeolite using in situ TEM for the first time. Variable temperature experiments observe the physical expansion of nanocrystals in response to changes in guest-molecule chemistry and temperature. Operando FTIR spectroscopy complements the observations and verifies the nature of adsorbed CO2 and structural changes at high temperatures. Quantum chemical modeling substantiates the effect of cation mobility and CO2 on the flexibility behavior of the structure. The results demonstrate the combined influences of temperature and CO2 on the structural flexibility consistent with experimental observations.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Applied
Peng Peng, Simona Moldovan, Aurelie Vicente, Valerie Ruaux, Maxime Debost, Han Hu, Hristiyan A. Aleksandrov, Georgi N. Vayssilov, Zi-Feng Yan, Svetlana Mintova
Summary: Nanosized MFI type zeolites were synthesized using Cu-containing complexes. The use of EDTA as a ligand promoted solubility and ensured exclusive configuration of copper-bearing chelate. EDTA-assisted MFI zeolite nanocrystals (Cu-MFIEDTA) had low silanol content due to flexible Si-O-Cu bonds. NH3 as a ligand resulted in extra framework [Cu delta+,,,O delta- ,,,Cu delta+]n clusters in the corresponding sample (Cu-MFI-NH3).
MICROPOROUS AND MESOPOROUS MATERIALS
(2023)
Article
Chemistry, Physical
Iskra Z. Koleva, Hristiyan A. Aleksandrov, Georgi N. Vayssilov
Summary: The mechanism of CO oxidation on platinum species supported on ceria or alumina was investigated using periodic density functional calculations. Various reaction paths involving different oxidation states of monoatomic species-Pt0, Pt2+, and Pt4+-as well as platinum clusters were modeled to understand the nature of the catalytically active species. The activation barriers of the reaction paths involving complexes of Pt2+ and Pt4+ cations were found to be the lowest, ranging from 22 to 35 kJ/mol. The calculations also revealed that the activation energies for platinum clusters with high CO coverage supported on ceria were low, while those on gamma-alumina or involving preadsorbed oxygen on the platinum cluster were significantly higher, ranging from 90 to 120 kJ/mol. The role of the oxidant in the reaction paths was discriminated, indicating that the activation barriers are low when the oxidants are platinum species and notably higher when the oxidants are Ce4+ cations.
Article
Chemistry, Physical
Nikola L. Drenchev, Elena Z. Ivanova, Mihail Y. Mihaylov, Hristiyan A. Aleksandrov, Georgi N. Vayssilov, Konstantin I. Hadjiivanov
Summary: In order to design efficient CO2 capture materials, a high adsorption capacity is necessary. It has been found that one Na+ site in NaY zeolite can attach two CO2 molecules, while one Ca2+ site in CaNaY zeolite can attach three CO2 molecules. The results show that CaY zeolites can be very effective CO2 capture materials, with the potential for practical use.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Konstantin Khivantsev, Ja-Hun Kwak, Nicholas R. Jaegers, Iskra Z. Koleva, Georgi N. Vayssilov, Miroslaw A. Derewinski, Yong Wang, Hristiyan A. Aleksandrov, Janos Szanyi
Summary: In this study, the mechanism of NO reduction using Cu/zeolite catalysts was investigated using spectroscopy, catalysis, and DFT calculations. It was found that nitrosyl ions are the key intermediates and nitrogen gas is produced through the intermediacy of the diazo N2H+ cation. The formation of NH4+ at low temperatures inhibits the catalytic cycle, while at higher temperatures, the cycle can continue.
Article
Chemistry, Inorganic & Nuclear
Stoyan P. Gramatikov, Petko St Petkov, Georgi N. Vayssilov
Summary: This study computationally investigates the distribution of germanium ions among the double four-membered rings (D4Rs) in SCM-14 germanosilicate and the influence of a structure-directing agent (SDA) on the stability of the material. The results show that clustered germanium structures are the most stable, and the position of fluoride anions has a significant destabilizing effect. Furthermore, the F-19 NMR chemical shift is not a reliable method for determining the germanium content in D4Rs.
INORGANIC CHEMISTRY FRONTIERS
(2022)
