scholarly journals Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

2020 ◽  
Vol 16 ◽  
pp. 798-808
Author(s):  
Dong Cai ◽  
ZhiHua Zhang ◽  
Yufan Meng ◽  
KaiLi Zhu ◽  
LiYi Chen ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Practical Method ◽  
Crystallographic Data ◽  
Glycyrrhetinic Acid ◽  
The Other ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Ester Derivative ◽  
Important Intermediate

In the present study, a practical method to prepare piperazinyl amides of 18β-glycyrrhetinic acid was developed. Two main procedures for the construction of important intermediate 8 are discussed. One procedure involves the amidation of 1-Boc-piperazine with 3-acetyl-18β-glycyrrhetinic acid, prepared by the reaction of 18β-glycyrrhetinic acid with acetic anhydride without any solvent at 130 °C. The other procedure to prepare compound 8 involves the amidation of 18β-glycyrrhetinic acid followed by the esterification with acetic anhydride. Finally, compound 8 underwent N-Boc deprotection to prepare product 4. To ascertain the scope of the reaction, another C-3 ester derivative 17 was tested under the optimized reaction conditions. Furthermore, the reasons for the appearance of byproducts were elucidated. Crystallographic data of a selected piperazinyl amide is reported.

p-Sulfonic acid calix[n]arene catalyzed synthesis of bioactive heterocycles: A review

2020 ◽  
Vol 24 ◽  
Author(s):  
Bubun Banerjee ◽  
Gurpreet Kaur ◽  
Navdeep Kaur
Keyword(s):  
Supramolecular Chemistry ◽  
Sulfonic Acid ◽  
Catalytic Efficiency ◽  
The Other ◽  
Reaction Conditions ◽  
Metal Free ◽  
Bioactive Scaffolds ◽  
Wide Range ◽  
Efficient Alternative ◽  
Bioactive Heterocycles

: Metal-free organocatalysts are becoming an important tool for the sustainable developments of various bioactive heterocycles. On the other hand, during last two decades, calix[n]arenes have been gaining considerable attention due to their wide range of applicability in the field of supramolecular chemistry. Recently, sulfonic acid functionalized calix[n] arenes are being employed as an efficient alternative catalyst for the synthesis of various bioactive scaffolds. In this review we have summarized the catalytic efficiency of p-sulfonic acid calix[n]arenes for the synthesis of diverse biologically promising scaffolds under various reaction conditions. There is no such review available in the literature showing the catalytic applicability of p-sulfonic acid calix[n]arenes. Therefore, we strongly believe that this review will surely attract those researchers who are interested about this fascinating organocatalyst.

scholarly journals Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1680
Author(s):  
Marta A. Andrade ◽  
Luísa M. D. R. S. Martins
Keyword(s):  
Heterogeneous Catalysts ◽  
Carbon Materials ◽  
Oxygen Species ◽  
Styrene Oxidation ◽  
Reaction Conditions ◽  
Reactive Metal ◽  
Catalytic Systems ◽  
Tert Butyl Hydroperoxide ◽  
Metal Organic ◽  
Important Intermediate

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.

scholarly journals Design of bifunctional quaternary phosphonium salt catalysts for CO2 fixation reaction with epoxides under mild conditions

2016 ◽  
Vol 18 (17) ◽  
pp. 4611-4615 ◽  
Author(s):  
Shiyao Liu ◽  
Naoki Suematsu ◽  
Keiji Maruoka ◽  
Seiji Shirakawa
Keyword(s):  
Co2 Fixation ◽  
Phosphonium Salt ◽  
Cyclic Carbonates ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Mild Conditions ◽  
Phosphonium Iodide ◽  
Fixation Reaction ◽  
Quaternary Phosphonium Salt

An efficient synthesis of cyclic carbonates from epoxides and CO2 under mild reaction conditions was achieved via the use of a designed bifunctional quaternary phosphonium iodide catalyst.

Localization of Stereotactic Targets by Microrecording of Thalamic Somatosensory Evoked Potentials

Neurosurgery ◽  
1991 ◽  
Vol 28 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Fumio Shima ◽  
Takato Morioka ◽  
Shozo Tobimatsu ◽  
Omiros Kavaklis ◽  
Motohiro Kato ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Median Nerve ◽  
Somatosensory Evoked Potentials ◽  
Practical Method ◽  
The Other ◽  
Basal Region ◽  
Thalamic Nuclei ◽  
Median Nerve Stimulation ◽  
Lower Amplitude ◽  
Stimulation Of

Abstract To improve the localization of stereotactic targets, somatosensory evoked potentials (SEPs) were recorded from the thalamus and subthalamic area using a specially designed semimicroelectrode in 61 patients and a conventional “macroclectrode” in 17 patients. By means of the semimicroelectrode, median nerve stimulation evoked two distinct SEPs, consisting of a diphasic wave with a huge positivity restricted to the nucleus ventrocaudalis (Vc) and a triphasic wave of lower amplitude with a major negativity in the ventral part of the nucleus ventrointermedius (Vim) and nucleus ventrooralis posterior (Vop) as well as the subthalamic lemniscal pathway. The Vim-Vc junction could thus be clearly delineated by an abrupt transition of SEPs from one type to the other with a precision of 1 mm. The parvicellular part of the Vc (Vcpc). situated in its basal region, was distinguishable from the Vc proper by a significant reduction of the positivity elicited by stimulation of the median nerve and by a rapid growth of a diphasic SEPs to stimulation of the posterior tibial nerve. In the other thalamic nuclei, stimulation of the median nerve elicited triphasic SEPs of a very small amplitude, suggesting a volume conduction current from the lemniscal pathway. With the macroclectrode, the positivity in the Vc was sensitive to electrode manipulation and the thalamic nuclei could not be distinctly outlined. SEP monitoring using the semimicroelectrode significantly improved the precision of target localization, which allowed minimizing of the volume of the therapeutic lesion without losing surgical effectiveness, while avoiding complications associated with increased penetration of the coagulating electrode. It is suggested that recording serial thalamic SEPs with the semimicroelectrode is a practical method to refine stereotactic targets in the thalamus.

Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

Aryl thiol-vinyl azide coupling reaction and thiol-vinyl azide coupling/cyclization cascade: efficient synthesis of β-ketosulfides and arene-fused 5-methylene-2-pyrrolidinone derivatives

2021 ◽  
Author(s):  
Yong Wang ◽  
Yu-Jiao Wang ◽  
Xian-Cheng Liang ◽  
Mei-Hua Shen ◽  
Hua-Dong Xu ◽  
...  
Keyword(s):  
Addition Reaction ◽  
Coupling Reaction ◽  
The Other ◽  
Efficient Synthesis ◽  
Coupling Process

The addition reaction of thiol to vinyl azide has been extensively studied. Variously substituted aryl thiols are all viable for this coupling process. The scope of the other partner is...

scholarly journals A Simple and Efficient Synthesis of Highly Substituted Indeno[1,2-b]pyrrole and Acenaphtho[1,2-b]pyrrole Derivatives by Tandem Three-Component Reactions

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 3031 ◽  
Author(s):  
Xiaodong Tang ◽  
Songlei Zhu ◽  
Ying Ma ◽  
Ren Wen ◽  
Lanqi Cen ◽  
...  
Keyword(s):  
Environmentally Benign ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Dicarbonyl Compounds ◽  
Pyrrole Derivatives ◽  
Three Component Reaction ◽  
High Yields ◽  
Operational Simplicity

A green, convenient and tandem procedure for the efficient synthesis of highly substituted indeno[1,2-b]pyrrole and acenaphtho[1,2-b]pyrrole derivatives by domino three-component reaction of tryptamine/benzylamine, 1,3-dicarbonyl compounds and ninhydrin/ acenaphthenequinone is described. The significant features of this procedure were characterized by mild reaction conditions, high yields, operational simplicity and it being environmentally benign.

Late-Stage Sulfoximination: Improved Synthesis of the Anticancer Drug Candidate Atuveciclib

Synthesis ◽  
2018 ◽  
Vol 51 (04) ◽  
pp. 971-975 ◽  
Author(s):  
Vincent Reboul ◽  
Thomas Glachet ◽  
Xavier Franck
Keyword(s):  
Anticancer Drug ◽  
Late Stage ◽  
Drug Candidate ◽  
Efficient Synthesis ◽  
Reaction Conditions

An efficient synthesis of racemic atuveciclib was accomplished in five steps with an excellent 51% overall yield, using cheap reagents and mild reaction conditions. The key sulfoximination reaction was realized during the last step of the synthesis from the corresponding sulfide.

A method to quantify hand-transmitted vibration exposure based on the biodynamic stress concept

2007 ◽  
Vol 221 (8) ◽  
pp. 847-861 ◽  
Author(s):  
R G Dong ◽  
D E Welcome ◽  
J Z Wu
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Practical Method ◽  
The Other ◽  
Equivalent Model ◽  
Frequency Effect ◽  
Vibration Exposure ◽  
Stress Cycle ◽  
Vibration Induced White Finger ◽  
Frequency Weightings

This study generally hypothesized that the vibration-induced biodynamic stress and number of its cycles in a substructure of the hand-arm system play an important role in the development of vibration-induced disorders in the substructure. As the first step to test this hypothesis, the specific aims of this study were to develop a practical method to quantify the biodynamic stress-cycle measure, to compare it with ISO-weighted and unweighted accelerations, and to assess its potential for applications. A mechanical-equivalent model of the system was established using reported experimental data. The model was used to estimate the average stresses in the fingers and palm. The frequency weightings of the stresses in these substructures were derived using the proposed stress-cycle measure. This study found the frequency dependence of the average stress distributed in the fingers is different from that in the palm. Therefore, this study predicted that the frequency dependencies of finger disorders could also be different from those of the disorders in the palm, wrist, and arms. If vibration-induced white finger (VWF) is correlated better with unweighted acceleration than with ISO-weighted acceleration, the biodynamic stress distributed in the fingers is likely to play a more important role in the development of VWF than is the biodynamic stress distributed in the other substructures of the hand-arm system. The results of this study also suggest that the ISO weighting underestimates the high-frequency effect on the finger disorder development but it may provide a reasonable risk assessment of the disorders in the wrist and arm.

RELATION ENTRE LE DEGRE DE POURRITURE, L’IMPEDANCE DES TISSUS ET LA DENSITE OPTIQUE D’UN EXTRAIT A L’ACETATE D’ETHYLE CHEZ LA RACINE DE LA LUZERNE

1976 ◽  
Vol 56 (1) ◽  
pp. 59-61
Author(s):  
C. RICHARD ◽  
C. GAGNON
Keyword(s):  
Ethyl Acetate ◽  
Optical Density ◽  
Negative Correlation ◽  
Practical Method ◽  
Significant Negative Correlation ◽  
The Other ◽  
Root Tissue ◽  
Strong Positive Correlation ◽  
Coefficient Of Correlation ◽  
Ethyl Acetate Extracts

The impedance of blocks of root tissue of several different rot indices was measured in alfalfa. In addition, optical density readings of ethyl acetate extracts of these blocks were made at 275 and 350 nm. Calculation of the coefficient of correlation between impedance and rot indices 2 to 5 indicates a significant negative correlation. On the other hand, a strong positive correlation was observed between high optical densities and elevated rot indices. While greater precision is achieved with optical density principally for low level of rot, experience indicates that a rot index estimated visually is the most rapid practical method.

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