604-32-0Relevant academic research and scientific papers
Complete 1H NMR assignment of cholesteryl benzoate
Pérez-Hernández, Nury,Becerra-Martínez, Elvia,Joseph-Nathan, Pedro
, p. 72 - 81 (2018)
The 750 MHz 1H NMR spectrum of cholesteryl benzoate (1b) could be assigned completely, which means all chemical shifts and all coupling constants, including some long-range values, were established. This task was possible by extracting many approximate coupling constant values in the overlapped spectrum region from an HSQC experiment, and using these values in the 1H iterative full spin analysis integrated in the PERCH NMR software. The task was facilitated using our published data for 3β-acetoxypregna-5,16-dien-20-one (3), the assignment data of the sesquiterpene benzoquinone dihydroperezone (2), also performed in the present study, which contains the same carbon atoms chain than cholesterol (1a), and an HSQC study of (25R)-27-deuteriocholesterol (1c) we prepared some 40 years ago. The HSQC values of 1c in combination with the coupling constants of 1b also allowed to completely assigning the spectrum of 1c. The complete assignment of 1b and 1c further provided the opportunity to estimate the hydrogen shifts induced upon benzoylation of cholesterol. Comparison of the experimental vicinal coupling constants of 1b with the values calculated using the Altona software provides an excellent correlation. In addition, a single crystal X-ray diffraction study of 1b provided the molecular conformation in the solid state, which revealed the side chain adopts an extended conformation.
Preparation of oxysterols by c–h oxidation of dibromocholestane with ru(Bpga) catalyst
Doiuchi, Daiki,Fujii, Yui,Hirai, Go,Igawa, Kazunobu,Makino, Kana,Takeda, Daiki,Tomooka, Katsuhiko,Uchida, Tatsuya,Yoritate, Makoto
supporting information, (2022/01/04)
Seven mono-and dihydroxycholesterols were prepared by direct C–H oxidation of the cholestane skeleton with a recently developed Ru(Bpga) catalyst (Ru(Bpga) = [RuCl (bpga) (PPh3 )] Cl; bpga = 2-(bis(pyridin-2-ylmethyl)amino)-N-(2,6-dimethylphenyl)acetamide)). Due to the high selectivity of the Ru(Bpga) complex for tertiary C–H, the reaction afforded a mixture of 25-, 20-, 17-, and 14-oxygenated cholesterols that could be easily separated by high-performance liquid chromatography. These results suggest that late-stage C–H oxidation could be a viable strategy for preparing candidate metabolites of biologically important molecules.
Construction of Cholesterol Oxime Ether Derivatives Containing Isoxazoline/Isoxazole Fragments and Their Agricultural Bioactive Properties/Control Efficiency
Xu, Hui,Zhang, Kong,Lv, Min,Hao, Meng
, p. 8098 - 8109 (2021/08/03)
To explore natural-product-based pesticidal candidates and high value-added application of cholesterol in agriculture, oximinoether derivatives of cholesterol-containing isoxazoline/isoxazole fragments (I-1～I-16 and II-1～II-18) were semiprepared by structural optimization of cholesterol. Their structures were characterized by optical rotation, high-resolution mass spectrometry (HRMS), IR, and 1H NMR spectroscopy. Particularly, the Z configurations of oxime fragments at the C-7 position of target compounds were undoubtedly determined by X-ray crystallography. Against Mythimna separata Walker, compounds 3e, I-8, I-14, and II-3 showed 2.4-2.7-fold growth inhibitory activity of the precursor cholesterol. Against Plutella xylostella Linnaeus, compounds I-6, I-7, and I-9 showed 2.4-2.7-fold oral toxicity of cholesterol. Against Aphis citricola Van der Goot, compounds 2e and II-15 exhibited 4.9 and 5.8-fold aphicidal activity of cholesterol, respectively. Notably, they showed good control effects (3.0-5.0-fold promising control efficiency of 1) against A. citricola in the greenhouse. Structure-activity relationships (SARs) suggested that the C-3 hydroxyl group and the C-7 position of cholesterol are two important modification sites. It will pave the way for future structural optimization and application of cholesterol derivatives as potential pesticidal agents in agriculture.
Preparation method of 7-dehydrocholesterol for production of vitamin D3
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Paragraph 0028-0033; 0036, (2021/04/07)
The invention particularly discloses a preparation method of 7-dehydrocholesterol for production of vitamin D3. The preparation method comprises the following steps: an esterification reaction, a bromination reaction, a debromination reaction and a saponification hydrolysis reaction. The esterification reaction comprises the following steps: adding cholesterol, an acid-binding agent and a solid catalyst into petroleum ether, carrying out heating to 45-50 DEG C in a nitrogen atmosphere, dropwise adding benzoyl chloride, performing heating to 78-82 DEG C after dropwise adding, conducting stirring for a reaction for 3-5 hours, adding distilled water to quench the reaction, performing filtering to obtain filter residues and a filtrate, extracting the filter residues with distilled water, concentrating an oil layer, then adding acetone, carrying out a reflux reaction for 30-40 minutes, conducting cooling to 20-30 DEG C, and performing filtering to obtain cholesterol benzoate; and soaking, filtering and drying the filter residues to obtain a solid desiccant, and repeatedly using the solid desiccant. The method has the advantage of facilitating cyclic utilization of the catalyst.
Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
supporting information, p. 7915 - 7922 (2021/05/03)
A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
Natural-product-based pesticides: Semisynthesis, structural elucidation, and evaluation of new cholesterol–matrine conjugates as pesticidal agents
Hao, Meng,Li, Tianze,Lv, Min,Xu, Hui,Xu, Jianwei,Zhang, Shaoyong
, (2021/09/07)
To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new cholesterol–matrine conjugates (I(a–e)–IV(a–e)) were prepared from two lead compounds cholesterol and matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3 and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0 folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads for further structural optimization as the insecticidal and aphicidal agents.
Benzyne-Mediated Esterification Reaction
Li, Yang,Shi, Jiarong,Zhao, Jinlong
supporting information, p. 7274 - 7278 (2021/10/01)
A benzyne-mediated esterification of carboxylic acids and alcohols under mild conditions has been realized, which is made possible via a selective nucleophilic addition of carboxylic acid to benzyne in the presence of alcohol. After a subsequent transesterification with alcohol, the corresponding esters can be produced efficiently. This benzyne-mediated protocol can be used on the modification of Ibuprofen, cholesterol, estradiol, and synthesis of nandrolone phenylpropionate. In addition, benzyne can also be used to promote lactonization and amidation reaction.
Mechanically induced solvent-free esterification method at room temperature
Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
, p. 5080 - 5085 (2021/02/05)
Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
A solvent-reagent selection guide for Steglich-type esterification of carboxylic acids
Jordan, Andrew,Sneddon, Helen F.,Sydenham, Jack,Whymark, Kyran D.
supporting information, p. 6405 - 6413 (2021/09/10)
The Steglich esterification is a widely employed method for the formation of esters under mild conditions. A number of issues regarding the sustainability of this transformation have been identified, chiefly the use of hazardous carbodiimide coupling reagents in conjunction with solvents with considerable issues such as dichloromethane (DCM) and N,N-dimethylformamide (DMF). To overcome these issues, we have developed a solvent-reagent selection guide for the formation of esters via Steglich-type reactions with the aim of providing safer, more sustainable conditions. Optimum reaction conditions have been identified after high-throughput screening of solvent-reagent combinations, namely the use of Mukaiyama's reagent (Muk) in conjunction with solvent dimethyl carbonate (DMC). The new reaction conditions were also exemplified through the synthesis of a small selection of building-block like molecules and includes the formation of t-butyl esters.
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
, p. 66 - 71 (2020/11/18)
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
