A One‐Pot Cross‐Pinacol Coupling/Rearrangement Procedure

A new catalytic retro‐pinacol/cross‐pinacol reaction, followed by subsequent rearrangement or deoxygenation of the intermediately formed vicinal diols, is described. This operationally simple one‐pot protocol allows isolation of geminal α,α‐diphenyl ketones or 1,1‐diphenyl alkenes with high yields and selectivities.     

船舶分油机模拟器设计与实现

针对分油机控制系统的仿真设计落后于当前先进控制系统的问题,提出了一种以Alfa Laval S系列分油机的EPC-60控制系统为母型的分油机模拟控制系统。介绍了分油机模拟器的整体结构,设计了以ARM为主控元件的仿真控制箱,实现了网络通信、液晶显示、按键扫描等功能。采用Visual C#编程语言在PC机上设计出仿真控制界面。实验结果表明：基于EPC-60为母型控制系统的分油机模拟器具有功能全、运行稳定、和实物相似度高的优点,能够实现轮机教学实验和海员培训的功能。     

Toward a synthesis of the antitumor macrolide peloruside A: a chiral pool approach for the C(1)-C(11) segment

Dihydroxylation of the glucose derived α,β-unsaturated lactones 6 and 13 was found to be on the α-face of the pyranolactone ring exclusively. The resulting dihydroxylated compound from 13 has been used in a synthesis of the lactone 4, which corresponds to C(1)-C(11) of peloruside A.     

ELECTRON-DONOR PROPERTIES OF SULFUR COMPOUNDS WITH A FEW DONOR SITES

Abstract

The structure and the coordination properties of sulfur compounds such as RS-(CH₂)n-SR, (I), n=1-10 and RS-(CH₂)nCOOR' (II), n=1,2 have been investigated by dipole moment, calorimetrie, IR-spectroscopy and cryoscopy methods.     

Ce-Loaded HZSM-5 Composite for Catalytic Deoxygenation of Algal Hydrolyzed Oil into Hydrocarbons and Oxygenated Compounds

Despite the extensive research into the catalytic uses of zeolite-based catalysts, these catalysts have a limited useful lifetime because of the deactivating effect of coke production. This study looks at the use of Cerium (Ce) loaded HZSM-5 zeolite catalysts in the hydrocarbon and oxygenated chemical conversion from Chlorella Vulgaris microalgae crude oil. Characterization of structure, morphology, and crystallinity was performed after the catalysts were manufactured using the impregnation technique. Soxhlet extraction was carried out to extract the crude oil of microalgae. Transesterification reaction was used to produce algal hydrolyzed oil (HO), and the resulting HO was put to use in a batch reactor at 300 °C, 1000 rpm, 7 bars of nitrogen pressure, a catalyst to the algal HO ratio of 15% (wt. %), and a retention time of 6 h. To determine which Ce-loaded HZSM-5 catalysts would be most effective in converting algal HO into non-oxygenated molecules (hydrocarbons), we conducted a series of tests. Liquid product characteristics were analyzed for elemental composition, higher heating value (HHV), atomic ratios of O/C and H/C, and degree of deoxygenation (DOD%). Results were categorized into three groups: product yield, chemical composition, and carbon number distribution. When Cerium was added to HZSM-5 zeolite at varying loading percentages, the zeolite’s acid sites became more effective in facilitating the algal HO conversion. The results showed that 10%Ce/HZSM-5 had the greatest conversion of the algal HO, the yield of hydrocarbons, HHV, and DOD% (98.2%, 30%, 34.05 MJ/Kg, and 51.44%, respectively) among all the synthesized catalysts in this research. In conclusion, the physical changes seen in the textural characteristics may be attributed to Cerium-loading on the parent HZSM-5; nevertheless, there is no direct association between the physical features and the hydrocarbons yield (%). The primary impact of Cerium alteration of the parent HZSM-5 zeolite was to change the acidic sites required to boost the conversion (%) of the algal HO in the catalytic deoxygenation process, which in turn increased the hydrocarbons yield (%), which in turn increased the HHV and DOD%.     

Reductive Deoxygenation of Carbonyl to Methylene

The reductive deoxygenation of aldehydes and ketones into the corresponding alkanes is accomplished by LiAlH4, in the presence of Lewis acid InBr3. It provides a convenient method to complete the transformation from carbonyl compounds to alkanes.     

Covalent Crosslinking of Graphene Quantum Dots by McMurry Deoxygenation Coupling

Graphene quantum dots were covalently crosslinked forming ensembles of a few hundred nanometers in size by McMurry deoxygenation coupling reactions of peripheral carbonyl functional moieties catalyzed by TiCl₄ and Zn powders in refluxing THF, as evidenced by TEM, AFM, FTIR, Raman and XPS measurements. Photoluminescence measurements showed that after chemical coupling, the excitation and emission peaks blue‐shifted somewhat and the emission intensity increased markedly, likely due to the removal of oxygenated species where quinone‐like species are known to be effective electron acceptors and emission quenchers.     

Deoxygenative Arylation of Carboxylic Acids by Aryl Migration

An unprecedented deoxygenative arylation of aromatic carboxylic acids has been achieved, allowing the construction of an enhanced library of unsymmetrical diaryl ketones. The synergistic photoredox catalysis and phosphoranyl radical chemistry allows for precise cleavage of a stronger C−O bond and formation of a weaker C−C bond by 1,5-aryl migration under mild reaction conditions. This new protocol is independent of substrate redox-potential, electronic, and substituent effects. It affords a general and promising access to 60 examples of synthetically versatile o-amino and o-hydroxy diaryl ketones under redox-neutral conditions. Furthermore, it also brings one concise route to the total synthesis of quinolone alkaloid, (±)-yaequinolone A2, and a viridicatin derivative in satisfying yields.     

Deoxygenation of 5-O-benzoyl-1,2-isopropylidene-3-O-imidazolylthiocarbonyl-α-d-xylofuranose using dimethyl phosphite: an efficient alternate method towards a 3′-deoxynucleoside glycosyl donor

An efficient radical deoxygenation reaction of thiocarbonylimidazolyl activated glycoside analogue using dimethyl phosphite as hydrogen source and radical chain carrier was performed as a key step in a multi step synthesis towards a common 3-deoxy glycosyl donor for 3′-deoxynucleosides. This method has safety and cost advantages compared to the generally used radical reduction reagents.     

Boron‐Catalyzed Regioselective Deoxygenation of Terminal 1,2‐Diols to 2‐Alkanols Enabled by the Strategic Formation of a Cyclic Siloxane Intermediate

The selective deoxygenation of polyols is a frontier in our ability to harness the stereochemical and structural complexity of natural and synthetic feedstocks. Herein, we describe a highly active and selective boron‐based catalytic system for the selective deoxygenation of terminal 1,2‐diols at the primary position, a process that is enabled by the transient formation of a cyclic siloxane. The method provides an ideal complement to well‐known catalytic asymmetric reactions to prepare synthetically challenging chiral 2‐alkanols in nearly perfect enantiomeric excess, as illustrated in a short synthesis of the anti‐inflammatory drug (R)‐lisofylline.