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161.
Jordan De Jesus Silva Niccolò Bartalucci Benson Jelier Samantha Grosslight Tobias Gensch Claas Schünemann Bernd Müller Paul C. J. Kamer Christophe Copéret Matthew S. Sigman Antonio Togni 《Helvetica chimica acta》2021,104(12):e2100200
A synthetic method for the palladium-catalyzed cyanation of aryl boronic acids using bench stable and non-toxic N-cyanosuccinimide has been developed. High-throughput experimentation facilitated the screen of 90 different ligands and the resultant statistical data analysis identified that ligand σ-donation, π-acidity and sterics are key drivers that govern yield. Categorization into three ligand groups – monophosphines, bisphosphines and miscellaneous – was performed before the analysis. For the monophosphines, the yield of the reaction increases for strong σ-donating, weak π-accepting ligands, with flexible pendant substituents. For the bisphosphines, the yield predominantly correlates with ligand lability. The applicability of the designed reaction to a wider substrate scope was investigated, showing good functional group tolerance in particular with boronic acids bearing electron-withdrawing substituents. This work outlines the development of a novel reaction, coupled with a fast and efficient workflow to gain understanding of the optimal ligand properties for the design of improved palladium cross-coupling catalysts. 相似文献
162.
Paola Zimmermann Crocomo Takahito Kaihara Soki Kawaguchi. Dr. Patrycja Stachelek Prof. Dr. Satoshi Minakata Prof. Dr. Piotr de Silva Prof. Dr. Przemyslaw Data Prof. Dr. Youhei Takeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(53):13390-13398
Novel electron donor–acceptor–donor (D-A-D) compounds comprising dibenzo[a,j]phenazine as the central acceptor core and two 7-membered diarylamines (iminodibenzyl and iminostilbene) as the donors have been designed and synthesized. Investigation of their physicochemical properties revealed the impact of C2 insertion into well-known carbazole electron donors on the properties of previously reported twisted dibenzo[a,j]phenazine-core D-A-D triads. Slight structural modification caused a drastic change in conformational preference, allowing unique photophysical behavior of dual emission derived from room-temperature phosphorescence and triplet–triplet annihilation. Furthermore, electrochemical analysis suggested sigma-dimer formation and electrochemical polymerization on the electrode. Quantum chemical calculations also rationalized the experimental results. 相似文献
163.
Godoi C. M. Santos M. C. L. Silva A. J. Tagomori T. L. Ramos A. S. de Souza R. F. B. Neto A. Oliveira 《Research on Chemical Intermediates》2021,47(2):743-757
Research on Chemical Intermediates - PdxCuy/C catalysts combinations were employed to CH4 partial oxidation in mild condition using a solid electrolyte reactor—alkaline fuel cell type. The... 相似文献
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M. J. Silva A. O. Sanches E. S. Medeiros L. H. C. Mattoso C. M. McMahan J. A. Malmonge 《Journal of Thermal Analysis and Calorimetry》2014,117(1):387-392
Cellulose nanofibrils (CNF) were isolated from cotton microfibrils (CM) by acid hydrolysis and coated with polyaniline (PANI) by in situ polymerization of aniline onto CNF in the presence of hydrochloride acid and ammonium peroxydisulfate to produce CNF/PANI. Nanocomposites of natural rubber (NR) reinforced with CNF and CNF/PANI were obtained by casting/evaporation method. TG analyses showed that coating CNF with PANI resulted in a material with better thermal stability since PANI acted as a protective barrier against cellulose degradation. Nanocomposites and natural rubber showed the same thermal profiles to 200 °C, partly due to the relatively lower amount of CNF/PANI added as compared to conventional composites. On the other hand, mechanical properties of natural rubber were significantly improved with nanofibrils incorporation, i.e., Young’s modulus and tensile strength were higher for NR/CNF than NR/CNF/PANI nanocomposites. The electrical conductivity of natural rubber increased five orders of magnitude for NR with the addition of 10 mass% CNF/PANI. A partial PANI dedoping might be responsible for the low electrical conductivity of the nanocomposites. 相似文献
168.
Robert W. Hicklin Tania L. López Silva Prof. Paul J. Hergenrother 《Angewandte Chemie (International ed. in English)》2014,53(37):9880-9883
Fenestranes are an intriguing class of highly strained molecules possessing a quaternary carbon with bonds that deviate from the canonical tetrahedral geometry. Herein we report the discovery that the natural product pleuromutilin can be used as a structurally complex starting material for the synthesis of a series of bridged cis,cis,cis,cis‐[4.5.5.5]‐ and cis,cis,cis,cis‐[4.5.7.5]oxafenestranes through a carbocation rearrangement cascade. X‐ray crystallographic analysis of several cis,cis,cis,cis‐[4.5.5.5]oxafenestranes shows a significant planarization of the central tetracoordinate carbon atom and demonstrates the influence of bridgehead substituents and bridging rings on planarity. 相似文献
169.
Inside Back Cover: Molecular Salt Effects in the Gas Phase: Tuning the Kinetic Basicity of [HCCLiCl]− and [HCCMgCl2]− by LiCl and MgCl2 (Angew. Chem. Int. Ed. 41/2014) 下载免费PDF全文
170.
Frontispiece: Engineering Catalyst Microenvironments for Metal‐Catalyzed Hydrogenation of Biologically Derived Platform Chemicals 下载免费PDF全文