Article
Chemistry, Multidisciplinary
Meng Li, Ruixue Zhang, Qiushan Gao, Huanfeng Jiang, Ming Lei, Wanqing Wu
Summary: Herein, a direct and efficient synthesis of diverse polysubstituted fused tetracyclic heterocycles with good functional group tolerance from diarylalkynes under different palladium catalytic systems is presented. The unprecedented intermolecular nucleopalladation of diarylalkynes through the highly selective sequential double insertion of isocyanide was achieved for the first time in this study. The practicality of this method was further demonstrated by the construction of various bioactive molecules and important structural motifs, with potential applications in materials science and biochemistry. In addition, density functional theory calculations revealed an interesting Pd walk during the cyclization process.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Alexander A. A. Lukoyanov, Andrey A. A. Tabolin, Yulia V. V. Nelyubina, Svetlana A. A. Aksenova, Alexey Yu. Sukhorukov
Summary: The reaction between cyclic nitronates and Kobayashi's aryne precursors leads to the formation of tricyclic benzene-fused nitroso acetals through [3 + 2]-cycloaddition. This process is regio- and stereoselective, yielding cycloadducts with up to four contiguous stereogenic centers. These nitroso acetals can be used as convenient precursors for the synthesis of valuable polysubstituted aminodiols through catalytic hydrogenolysis of the N-O bonds. Furthermore, protic acids cause the unusual fragmentation of the cyclic nitroso acetal moiety, leading to the synthesis of a previously unknown hexahydrobenzo[4,5]isoxazolo[2,3-a]azepine scaffold through heterolytic N-O bond cleavage and Beckmann-type reaction.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Sambasivarao Kotha, Usha Nandan Chaurasia, Saima Ansari
Summary: This study elucidates the stereochemical outcome of different routes in the synthesis process, through single-crystal X-ray diffraction analysis of six crystal structures involved.
Article
Chemistry, Applied
Xiong-Wei Liu, Xiao-Tong Lin, Cheng Zhao, Xiao-Wei Hu, Yi-Bing Xu, Yi-Lin Zheng, Xin-Ni Liu, Guo-Shu Chen, Long Chen, Yun-Lin Liu
Summary: The construction of benzopyrone-fused hydrobenzofuranones via DABCO-catalyzed [3+2] cyclization/deformylation cascade of p-quinols with 3-formylchromones is described. The reaction provides the desired products in 53-90% yields with complete diastereoselectivities under mild conditions. Furthermore, an enantioselective version with 81% ee is also achieved in the presence of Takemoto's chiral thiourea catalyst.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Inorganic & Nuclear
Minling Zhong, Jie Zhang, Zhenpin Lu, Zuowei Xie
Summary: A novel boracycle bearing an electron precise B-B bond was synthesized and used as a strain-release compound for diboration of alkenes and alkynes, leading to ring-expansion products. Additionally, when bis(trimethylsilyl) acetylene was employed, an allene-functionalized six-membered boracycle was obtained. DFT calculations were conducted to illuminate the reaction mechanism.
DALTON TRANSACTIONS
(2021)
Article
Multidisciplinary Sciences
Martijn P. van den Heuvel, Dirk Jan Ardesch, Lianne H. Scholtens, Siemon C. de Lange, Neeltje E. M. van Haren, Iris E. C. Sommer, Udo Dannlowski, Jonathan Repple, Todd M. Preuss, William D. Hopkins, James K. Rilling
Summary: This study examines the neural connectivity underlying cognitive abilities in chimpanzees and humans. It finds that chimpanzees with higher cognitive skills have stronger connectivity among brain networks associated with comparable abilities in humans. The study also identifies differences in brain networks related to specialized functions between the two species. These findings suggest that core neural systems for cognition may have evolved before the divergence of chimpanzees and humans, along with distinct investments in other brain networks.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Chemistry, Organic
Zhimin Xing, Bowen Fang, Shangwen Luo, Xingang Xie, Xiaolei Wang
Summary: Seven-membered polycyclic architectures, commonly found in natural products and molecular drugs, are challenging targets in synthesis. This study presents a base-induced ring expansion as a general strategy for constructing a wide range of fused seven-membered ring systems. The successful synthesis of two sesquiterpenoids, plecarpenene and plecarpenone, demonstrates the efficacy of this method for constructing fused bicyclo[5.3.0]decane skeletons.
Article
Engineering, Industrial
Chia-Huang Wu, Tseng-Chang Yen, Kuo-Hsiung Wang
Summary: This paper compares four retrial power supply systems with general repair time, warm standby units, and imperfect coverage possibility. The steady-state probabilities and availabilities of these systems are derived and a comparative analysis of availability and cost-benefit ratio is presented. Based on numerical results, the optimal retrial system and management insights for decision making are provided.
RELIABILITY ENGINEERING & SYSTEM SAFETY
(2021)
Article
Management
Fanyong Meng, Beibei Xiong
Summary: This paper introduces a cross efficiency evaluation method for a general two-stage system, which includes various models to express the efficiency and consistency of the system comprehensively. The method has been applied to the analysis of nine top universities in China, showing its effectiveness and applicability.
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH
(2021)
Article
Chemistry, Organic
Keisuke Hosoya, Keita Iida, Minami Odagi, Kazuo Nagasawa
Summary: Recent advances in methodologies for constructing the characteristic tetracyclic hydrocarbazole core structure with a fused pyrrolidine ring at C9a position have attracted considerable interest due to the anti-tumor and analgesic activities exhibited by the Strychnos alkaloid minfiensine and its analogs.
Article
Engineering, Mechanical
Jia Guo, Li Wang, Iori Fukuda, Kohju Ikago
Summary: Damping, a complex phenomenon in structural analysis and design, is modeled using a data-driven framework in this paper. The framework includes pre-defined dictionaries, clustering technique, and a two-stage regression procedure. Numerical examples and experiments demonstrate the effectiveness and efficiency of this approach for general damping systems.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Review
Chemistry, Multidisciplinary
Bohdan Biletskyi, Pierre Colonna, Kevin Masson, Jean-Luc Parrain, Laurent Commeiras, Gaelle Chouraqui
Summary: In this review, the release of ring strain in cyclobutane and cyclopropane derivatives is highlighted as a way to rapidly increase molecular complexity. The state-of-the-art of ring expansions involving three- and four-membered cycles is discussed, with an emphasis on reaction types and mechanisms. Selected examples are used to illustrate the synthetic potential of this elegant synthetic tool.
CHEMICAL SOCIETY REVIEWS
(2021)
Article
Computer Science, Hardware & Architecture
Parul Trivedi, Brij Bihari Tiwari
Summary: This work presents a new design approach for a four-stage ring Voltage-Controlled Oscillator (VCO) for Orthogonal Frequency Division Multiplexing (OFDM) systems, which is suitable for low-phase noise and low-power applications. The proposed ring VCO improves phase noise by limiting the output current of the delay cell to a narrow portion of the output waveform, while maintaining low power consumption due to the complementary nature of the delay cell. The designed and simulated VCO achieves a tuning frequency range of 112-362MHz, with a control voltage range of 0.0-1.0V and power consumption of 1.07mW. At a 1MHz offset frequency, the phase noise is reduced to -109.36dBc/Hz. The proposed design is validated through Process-Voltage-Temperature (PVT) analysis, and it exhibits a Figure of Merit (FOM) of -160.24dBc/Hz and a total area of 0.00085mm(2).
JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS
(2023)
Article
Optics
P. A. Ameen Yasir
Summary: General first-order optical systems can be realized using free propagation transformations and thin lenses. By placing nine thin lenses in five transverse planes, the system can be implemented using five spatial light modulators (SLMs) to achieve any first-order optical system.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION
(2021)
Article
Agricultural Economics & Policy
Michael Young, John Young, Ross S. Kingwell, Philip E. Vercoe
Summary: This study compares two whole farm optimization models of an Australian mixed enterprise farming system, one of which takes into account weather-year variation and the short-term tactical management responses, while the other model assumes every year is an expected weather-year. The comparison shows that the model considering weather-year variation can increase expected farm profit by about 18%.
AUSTRALIAN FARM BUSINESS MANAGEMENT JOURNAL
(2023)
Article
Chemistry, Organic
HtooTint Wai, Kang Du, Jason Anesini, Wan Shin Kim, Alan Eastman, Glenn C. Micalizio
Article
Chemistry, Organic
Kang Du, Matthew J. Kier, Arnold L. Rheingold, Glenn C. Micalizio
Article
Chemistry, Organic
Adam B. Millham, Matthew J. Kier, Robert M. Leon, Rajdip Karmakar, Zachary D. Stempel, Glenn C. Micalizio
Article
Chemistry, Organic
Robert M. Leon, Divya Ravi, Jennifer S. An, Carmen L. del Genio, Arnold L. Rheingold, Arti B. Gaur, Glenn C. Micalizio
Article
Chemistry, Organic
Rajdip Karmakar, Arnold L. Rheingold, Glenn C. Micalizio
Article
Multidisciplinary Sciences
Wan Shin Kim, Zachary A. Shalit, Sidney M. Nguyen, Emmalie Schoepke, Alan Eastman, Thomas P. Burris, Arti B. Gaur, Glenn C. Micalizio
NATURE COMMUNICATIONS
(2019)
Article
Chemistry, Multidisciplinary
Kang Du, Matthew J. Kier, Zachary D. Stempel, Valer Jeso, Arnold L. Rheingold, Glenn C. Micalizio
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Chemistry, Organic
Adam B. Millham, Chinmay P. Bhatt, Glenn C. Micalizio
Article
Chemistry, Organic
Zachary A. Shalit, Lucas C. Valdes, Wan Shin Kim, Glenn C. Micalizio
Summary: The total synthesis of (+)-03219A, a rare Delta(8,9)-pregnene isolated from marine-derived Streptomyces sp. SCSIO 03219, involved a series of transformations from epichlorohydrin to an ent-estrane, then to a nat-androstane, ultimately establishing the natural product target. The success of these studies relied on the implementation of two rearrangement processes to formally invert the quaternary center at C13 and establish the C10 quaternary center.
Article
Chemistry, Medicinal
Lauren E. Markham, Jessica D. Tolbert, F. Jon Kull, Charles R. Midgett, Glenn C. Micalizio
Summary: The chiral conformation of palmitoleic acid when bound to the bacterial pathogen Vibrio cholerae's virulence genes master regulator ToxT served as inspiration for designing a novel class of fatty acid mimetics. The best mimetic, based on a chiral hydrindane, was discovered to be a potent inhibitor of the target. Synthetic chemistry utilizing stereoselective annulative cross-coupling reactions and dissolving metal reduction was crucial in establishing the C13 and C9 stereocenters for these studies.
ACS MEDICINAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Andrea R. Bucknam, Glenn C. Micalizio
Summary: The asymmetric de novo synthesis of octanorcucurbitacin B, a cucurbitane natural product, was achieved using a novel approach. This approach bypassed the traditional biosynthetic hypothesis and directly accessed the cucurbitane skeleton. The synthesis involved a sequence of reactions, ultimately resulting in the conversion to octanorcucurbitacin B.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
HtooTint Wai, Thomas Koelblen, Matthew E. Hayes, Thomas P. Burris, Glenn C. Micalizio
Summary: Progress has been made in the asymmetric synthesis of euphanes, and a C14-desmethyl euphane system with five differentially substituted and electronically distinct alkenes has been successfully prepared. The route employed involves sequential metallacycle-mediated annulative cross-coupling, double asymmetric Bronsted acid mediated intramolecular Friedel-Crafts alkylation, and an oxidative rearrangement to establish the required C10 quaternary center. These studies have also led to the discovery of a novel euphane-based modulator of the Liver X Receptor.
Article
Chemistry, Organic
Adam B. Millham, Glenn C. Micalizio
Summary: Efforts have been made to introduce C17 beta-substitution by late-stage functionalization of stereodefined steroidal D-ring vinylepoxides in a program aiming to establish a common sequence of C-C bond-forming reactions for asymmetric construction of tetracyclic triterpenoid natural products and related synthetic systems. Cyanocuprates were found to participate in syn-S(N)2' reactions resulting in products with various C17 beta-substituents and a beta-OH at C14.
Article
Chemistry, Organic
Zachary A. Shalit, Glenn C. Micalizio