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Catalytic Asymmetric Michael Addition of Aldehydes to Nitroalkenes
Published in Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera, Catalytic Asymmetric Reactions of Conjugated Nitroalkenes, 2020
Irishi N. N. Namboothiri, Meeta Bhati, Madhu Ganesh, Basavaprabhu Hosamani, Thekke V. Baiju, Shimi Manchery, Kalisankar Bera
Chen and co-workers designed, synthesized and evaluated pyrrolidine-camphor organocatalysts C22 and C23 for the asymmetric Michael reaction of aldehydes 5 to nitroalkenes 1 (Scheme 2.18). The catalyst C22 was found to be the most effective for α,α-disubstituted aldehydes 5 in the presence of 20 mol% benzoic acid under solvent-free conditions,74 whereas the catalyst C23 gave best results with unsubstituted aldehydes providing the desired Michael products 6 in high yields (up to 94%) and stereoselectivities (up to 99% ee).75 Here, the pyrrolidine unit of the bifunctional organocatalyst C23 reacts with the aldehyde 5 to form nucleophilic enamine, and the 4-hydroxy group of the catalyst C23 activates the nitro group through hydrogen bonding to organize a favorable transition state model. The neighboring rigid bicyclic camphor scaffold serves as an efficient stereocontrolling element. The approach of the nitroalkene from the less-hindered Si-face of the enamine would produce the observed stereochemistry (TS-11, Scheme 2.18).
Emergency Monitoring of Marine Oil Spill Accidents
Published in Lin Mu, Lizhe Wang, Jining Yan, Information Engineering of Emergency Treatment for Marine Oil Spill Accidents, 2019
Lin Mu, Lizhe Wang, Jining Yan
The average content of aromatic hydrocarbons and naphthenic-aromatic hydrocarbons in petroleum is 20% ∼ 45%. Aromatic hydrocarbons contain only aromatic rings and chain bases, and the common types of aromatic hydrocarbons identified in petroleum include benzene of monocyclic aromatic hydrocarbons (CnC2n−6), biphenyl of polycyclic aromatic hydrocarbons, naphthalene of polycyclic aromatic hydrocarbons (bicyclic CnC2n−12), anthracene and phenanthrene (tricyclic CnC2n−12), and benzanthracene and chrysene (tetracyclic CnC2n−24) and aromatic hydrocarbons with up to 8 condensed aromatic rings. Among them, the content of benzene, naphthalene and phenanthrene are the highest, and the main types are alkyl derivatives rather than parents. For example, the main component of monocyclic aromatic hydrocarbons is toluene rather than benzene. Naphthenic aromatic hydrocarbons contain one or several condensed aromatic rings and are thickened with saturated rings and chain alkyls. The most abundant in petroleum are bicyclic (an aromatic ring and a saturated ring) indane and tetralin and their methyl derivatives. In petroleum, the most important is tetracyclic and pentacyclic naphthenic aromatic hydrocarbons, most of which are related to steroids and terpenes and are biomarkers. Their content and distribution characteristics are important indicators for studying the origin of petroleum and oil-source correlation.
Terpenoids Against Infectious Diseases
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Sanhita Ghosh, Kamalika Roy, Chiranjib Pal
Natural bicyclic monoterpenoids such as (±)-camphor (Table 8.1) have been chosen as promising starting materials for synthesizing new antiviral compounds. The 1-norbornylamines (Table 8.1) have been shown to exhibit satisfactory inhibitory effects against IAV, whereas its effects against the African swine fever virus were comparatively moderate (Martinez et al. 1995). Coumarins substituted with camphanic acid (Table 8.1), a novel class of compounds could be used as effective antiviral agents against both the wild-type and drug-resistant Human Immunodeficiency Virus (HIV-1) strains. The 3′ and 4′ camphanoyl groups were found to be critical in maintaining the high potency of this class of antivirals (Salakhutdinov et al. 2017; Xie et al. 2001).
Pyrolysis behaviors and product distribution of Shengli Lignite at different heating rate and final temperature by TG-FTIR and Py-GC-MS
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Zhenyong Miao, Yongjiang Wan, Qiongqiong He, Zhen Pei, Xiaoqian Zhu
The products from the pyrolysis process at 800°C, 600°C, and 400°C with a heating rate of 20°C/min are shown in Figure 3 and Table 3. It can be seen that olefins, ketones, alcohols, alkanes, benzene, naphthalene, acids, and their derivatives were the main pyrolysis products. At every temperature, bicyclic compounds, monocyclic aromatic compounds and long-chain aliphatic compounds with more than 10 carbon atoms, such as dodecane, 2-methylnaphthalene, and benzothiazole, were detected by the GC-MS chromatogram in the range of 10–25 min, in which 1-methyl-naphthalene was always the most important compound.
Rhodium catalysis in the synthesis of fused five-membered N-heterocycles
Published in Inorganic and Nano-Metal Chemistry, 2020
Navjeet Kaur, Neha Ahlawat, Yamini Verma, Pranshu Bhardwaj, Pooja Grewal, Nirmala Kumari Jangid
Bates and Lim[161] synthesized piperidine derivative (229) in high diastereoselectivity via double bond reduction of the allylamine (227) followed by intramolecular reductive amination with Wilkinson’s catalyst (Scheme 53). The piperidine produced nupharamine, nuphar alkaloid, and the bicyclic heterocycle (230). The saturated analog (231) was formed by the reduction of bicyclic heterocyclic compound (230) with lithium aluminum hydride.[18]