Synthetic Approaches to Chiral Non-C
          2-symmetric N-Heterocyclic Carbene Precursors

N-Heterocyclic carbenes and their metal complexes have found applications in many organic transformations. Apart from the privileged C 2-symmetry present in modern enantioselective catalysis, ligands bearing C 1-symmetry have witnessed growing attention due to the better control of process stereoselectivity in many cases. The present review summarizes, for the first time, the seminal synthetic efforts for the preparation of N-heterocyclic carbene precursors exhibiting C 1-symmetry. The well-established methods will be discussed in the light of recent achievements, giving a direct opportunity for comparison of the existing methods, and simultaneously a chance to find the best synthetic pathway for the ideal chiral ligand.1 Introduction2 Five-Membered Rings2.1 Five-Membered Saturated (Imidazolinium) Ring2.1.1 Amino Alcohol Derivatives2.1.2 Amino Acid Derivatives2.1.3 Amine and Diamine Derivatives2.2 Five-Membered Unsaturated Ring2.2.1 Cyclization Strategy2.2.2 Functionalization of the Existing N-Imidazole Ring3 Triazolium Salts3.1 Substitution in Oxadiazolium Salts3.2 Lactam-Derived Triazolium NHC (The Leeper and Knight Methodology)3.3 Monoterpenoid-Derived NHC Triazolium Salts3.4 Modifications of the Existing Triazole Ring4 Thiazole-Derived Salts4.1 Cyclization of a Thiazolium Ring4.2 Modifications of the Existing Thiazole Ring5 Summary and Outlook

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Aryl-substituted Triarsiranes: Synthesis and Reactivity

10.26434/chemrxiv.13176842 ◽

2020 ◽

Author(s):

André Schumann ◽

Jonas Bresien ◽

Malte Fischer ◽

Christian Hering-Junghans

Keyword(s):

Organic Chemistry ◽

Electronic Structure ◽

Heterocyclic Carbenes ◽

Synthetic Approaches ◽

Inorganic And Organic

Cyclotriarsanes are rare and limited synthetic approaches have hampered reactivity studies on these systems. Described in here is a scalable synthetic protocol towards (AsAr)3 (Ar = Dip, 2,6-iPr2-C6H3; Tip, 2,4,6-iPr3-C6H2), which allowed to study their reactivity towards [Cp2Ti(C2(SiMe3)2], affording titanocene diarsene complexes and towards N-heterocyclic carbenes (NHCs) to give straightforward access to a variety of NHC-arsinidene adducts. The electronic structure of the titanium diarsene complxes has been studied and they are best described as Ti(IV) species with a doubly reduced As2Ar2 ligand. These findings will make (AsAr)3 valuable precursors in the synthetic inorganic and organic chemistry.

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The Republic

The Oxford Handbook of Plato ◽

10.1093/oxfordhb/9780190639730.013.11 ◽

2019 ◽

pp. 205-229

Author(s):

Dominic Scott

Keyword(s):

Political Theory ◽

Left Behind ◽

Ideal State ◽

The Republic ◽

Individual Justice ◽

The Individual ◽

Political Right ◽

First Time ◽

The Ideal

This chapter presents a reading of Plato’s Republic. The Republic is among Plato’s most complex works. From its title, the first-time reader will expect a dialogue about political theory, yet the work starts from the perspective of the individual, coming to focus on the question of how, if at all, justice contributes to an agent’s happiness. Only after this question has been fully set out does the work evolve into an investigation of politics—of the ideal state and of the institutions that sustain it, especially those having to do with education. But the interest in individual justice and happiness is never left behind. Rather, the work weaves in and out of the two perspectives, individual and political, right through to its conclusion. All this may leave one wondering about the unity of the work. The chapter shows that, despite the enormous range of topics discussed, the Republic fits together as a coherent whole.

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Philosophy and Education

The Paideia Archive: Twentieth World Congress of Philosophy ◽

10.5840/wcp20-paideia199829473 ◽

1998 ◽

pp. 32-36

Author(s):

Luciana Bellatalla

Keyword(s):

Western Culture ◽

Cultural Tradition ◽

The World ◽

Dialogic Approach ◽

First Time ◽

The Ideal

From its first appearance in western culture, philosophy has been considered able to build up reality, to educate people, and to disclose truth. Plato proposed philosophers as governors in life-long pursuit of philosophical learning. Socrates was the ideal paradigm of an educating philosopher: he tried to wake up human minds so that they could be aware of themselves and of the world, criticizing tradition and prejudices in a logically consistent perspective. A critical and dialogic approach—not by mere chance defined as "Socratic"—to problems has been considered until now the most profitable method of teaching. Socrates is a pioneer in discussing the question of a philosophical (paideia), as he defined his method "maieutic." He was not an authoritarian teacher, but a sparring partner in the process of self-education. Moreover, he considered himself as the most learned and, at the same time, the wisest in Greece, just because he was conscious of his ignorance. Therefore, he understood for the first time in our cultural tradition that knowledge is an endless process rather than a product, within marked bounds.

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The Activities of the Tube Feet of Asterias Rubens L

Journal of Cell Science ◽

10.1242/jcs.s3-88.1.1 ◽

1947 ◽

Vol s3-88 (1) ◽

pp. 1-14

Author(s):

J. E. SMITH

Keyword(s):

Forward Direction ◽

The Other ◽

Asterias Rubens ◽

Ideal Form ◽

First Time ◽

Intrinsic Musculature ◽

Tube Feet ◽

Postural Muscles ◽

The Ideal

1. An account is given of the muscular anatomy of the foot and ampulla of Asterias rubens. An intrinsic musculature of the sucker figured by Cuénot (1891) and Chadwick (1923) is shown not to be present; on the other hand, postural muscles responsible for orientating the podium, levator fibres which ‘cup’ the sucker, and radial fibres which flatten it are described and figured for the first time. 2. The role of the different muscle systems, the collagen connective tissue, and the fluid of the hydrocoel in protracting and retracting the foot, and in effecting the attachment and detachment of the sucker, is discussed. 3. Evidence is presented, to show that postural pointing of the foot is brought about by the contraction of a ring of muscles encircling the base of the podium. The orienting muscles are functionally, but not anatomically, distinct from the longitudinal fibres of the retractor sheath. 4. The ambulatory step is shown to comprise a series of linked phases of static posture and of movement. Each phase is characterized by the contraction of one member of each of the two opposing pairs of muscles engaged in the development of the step. The two pairs of muscles are (1) the anterior and posterior orienting fibres, and (2) the protractors and retractors of the foot. In its ideal form the step comprises four phases of static posture alternating with four movements. Each movement is ushered in by a reversal of the contraction-relaxation relationships of one of the two pairs of opposing muscle systems. Four such changes are possible and they occur in a sequence that ensures the orderly succession of the four movements of protraction, swing back, retraction, and swing forward, of which movements the idealized stepping cycle is composed. 5. The actual locomotory step departs from the ideal form in two respects: (1) it is liable to become disrupted by a delay in the initiation of the protraction or of the backswing movement, and (2) withdrawal of the podium occurs simultaneously with its re-orientation in the forward direction. It is pointed out that these variations are explicable on the assumption that, in the two series of opposing muscle pairs, the retractor fibres are more readily excited to contract than are their antagonists, and the anterior postural muscles than the posterior postural fibres.

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Synthetic Approaches for Accessing Rare-Earth Analogues of UiO-66

Chemical Communications ◽

10.1039/d1cc01552d ◽

2021 ◽

Author(s):

Rafael P. Donnarumma ◽

Sahara Frojmovic ◽

Paola Marino ◽

Hudson de Aguiar Bicalho ◽

Hatem M. Titi ◽

...

Keyword(s):

Rare Earth ◽

Synthetic Approaches ◽

First Time

Rare-earth (RE) analogues of UiO-66 with non-functionalised 1,4-benzenedicarboxylate linkers are synthesised for the first time, and a series of synthetic approaches is provided to troubleshoot the synthesis. RE-UiO-66 analogues are...

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Franciscan Books and their Readers

10.5117/9789463729512 ◽

2022 ◽

Author(s):

René Hernández

Keyword(s):

Space Form ◽

Northern Italy ◽

Ideal Space ◽

Skilled Readers ◽

Personal Library ◽

Key Aspects ◽

Cultural Agency ◽

First Time ◽

The Ideal

The book explores the manuscripts written, read, and studied by Franciscan friars from the thirteenth to the fifteenth centuries in Northern Italy, and specifically Padua, assessing four key aspects: ideal, space, form and readership. The ideal is studied through the regulations that determined what manuscripts should aim for. Space refers to the development and role of Franciscan libraries. The form is revealed by the assessment of the physical configuration of a set of representative manuscripts read, written, and manufactured by the friars. Finally, the study of the readership shows how Franciscans were skilled readers who employed certain forms of the manuscript as a portable, personal library, and as a tool for learning and pastoral care. By comparing the book collections of Padua’s reformed and unreformed medieval Franciscan libraries for the first time, this study reveals new features of the ground-breaking cultural agency of medieval friars.

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N-Heterocyclic carbenes from ylides of indolyl-imidazolium, azaindolyl-imidazolium, and indolyl-triazolium salts, and their borane adducts

Tetrahedron ◽

10.1016/j.tet.2014.09.035 ◽

2014 ◽

Vol 70 (45) ◽

pp. 8672-8680 ◽

Cited By ~ 19

Author(s):

Nazar Pidlypnyi ◽

Sebastian Wolf ◽

Ming Liu ◽

Kari Rissanen ◽

Martin Nieger ◽

...

Keyword(s):

Heterocyclic Carbenes ◽

Triazolium Salts

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The Temperature-Dependent Ideal Shear Strength of Solid Single Crystals

Journal of Applied Mechanics ◽

10.1115/1.4038884 ◽

2018 ◽

Vol 85 (3) ◽

Cited By ~ 1

Author(s):

Tianbao Cheng ◽

Daining Fang ◽

Yazheng Yang

Keyword(s):

Shear Strength ◽

Theoretical Model ◽

Melting Point ◽

Single Crystals ◽

Elevated Temperatures ◽

Absolute Zero ◽

Temperature Dependent ◽

Temperature Changes ◽

First Time ◽

The Ideal

Knowledge of the ideal shear strength of solid single crystals is of fundamental importance. However, it is very hard to determine this quantity at finite temperatures. In this work, a theoretical model for the temperature-dependent ideal shear strength of solid single crystals is established in the view of energy. To test the drawn model, the ideal shear properties of Al, Cu, and Ni single crystals are calculated and compared with that existing in the literature. The study shows that the ideal shear strength first remains approximately constant and then decreases almost linearly as temperature changes from absolute zero to melting point. As an example of application, the “brittleness parameter” of solids at elevated temperatures is quantitatively characterized for the first time.

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Seasonal Variability of Genistein and 6-Hydroxykynurenic Acid Contents in Ginkgo biloba Leaves from Different Areas of China

Natural Product Communications ◽

10.1177/1934578x1701200823 ◽

2017 ◽

Vol 12 (8) ◽

pp. 1934578X1701200

Author(s):

Jian B. Yao ◽

Xin Du ◽

Hui H. Jin ◽

Ling Fang ◽

Hui Min ◽

...

Keyword(s):

Phosphoric Acid ◽

Ginkgo Biloba ◽

Quality Analysis ◽

Natural Occurrence ◽

Sophora Flavescens ◽

Relative Lack ◽

Harvesting Time ◽

Quality Marker ◽

First Time ◽

The Ideal

Refined extracts of Ginkgo biloba L. leaves can protect brain tissue from diverse types of tissue damage. Preliminary experiments identified 6-hydroxykynurenic acid (6-HKA) as a central contributor to this effect, and thus as a potential active marker for drug quality analysis. In contrast, genistein is a negative quality marker for this drug, as high contents of this compound in G. biloba leaves samples are in most cases caused by adulteration with Sophora flavescens Aiton, which is added to the extract by unlawful producers in order to boost its content in flavones, which serve as a quality marker. Some publications even dispute the natural occurrence of genistein in G. biloba leaves altogether, thus claiming that its presence even in trace amounts would prove adulteration. The present study aims to resolve the influence of harvesting time and location on the contents of genistein and 6-HKA - HPLC: Agilent SB-C18 column (5 μm, 4.6×250 mm); phosphoric acid pH2.5, acetonitrile, methanol, gradient; 1 mL/min; 25°C; UV 350 nm - in G. biloba leaves. The lowest contents of 6-HKA were observed in July and August, whereas the maximum was reached in May and October. In the case of genistein - its natural occurrence in G. biloba leaves could be demonstrated under controlled conditions for the first time - the lowest contents were found in May and June, whereas the highest were detected in September and October. These results show that harvesting of G. biloba leaves for pharmaceutical use should be avoided in July and August because of the reduced 6-HKA content, as well as in September and October, the season of highest genistein production. Due to both favorable 6-HKA production and a relative lack of genistein, May was identified as the ideal harvesting month for G. biloba leaves.

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Neutrosophic Modeling of Talcott Parsons’s Action and Decision-Making Applications for It

Symmetry ◽

10.3390/sym12071166 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1166

Author(s):

Cahit Aslan ◽

Abdullah Kargın ◽

Memet Şahin

Keyword(s):

Decision Making ◽

Similarity Measure ◽

Similarity Measures ◽

Theory Of Action ◽

Grand Theory ◽

Important Place ◽

Social Theories ◽

Measure Of Similarity ◽

First Time ◽

The Ideal

The grand theory of action of Parsons has an important place in social theories. Furthermore, there are many uncertainties in the theory of Parsons. Classical math logic is often insufficient to explain these uncertainties. In this study, we explain the grand theory of action of Parsons in neutrosociology for the first time. Thus, we achieve a more effective way of dealing with the uncertainties in the theory of Parsons as in all social theories. We obtain a similarity measure for single-valued neutrosophic numbers. In addition, we show that this measure of similarity satisfies the similarity measure conditions. By making use of this similarity measure, we obtain applications that allow finding the ideal society in the theory of Parsons within the theory of neutrosociology. In addition, we compare the results we obtained with the data in this study with the results of the similarity measures previously defined. Thus, we have checked the appropriateness of the decision-making application that we obtained.

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