Deuterium Labelling to Extract Local Stereochemical Information by VCD Spectroscopy in C-D Stretching Region: A Case Study of Sugars

2022 ◽  
Author(s):  
Mohamad Zarif Mohd Zubir ◽  
Nurul Fajry Maulida ◽  
Yoshihiro Abe ◽  
Yuta Nakamura ◽  
Mariam Abdelrasoul ◽  
...  
Keyword(s):  
Chiral Center ◽  
Deuterium Labelling ◽  
Chiral Centers

Stereochemical elucidation of molecules with multiple chiral centers is difficult. Even with VCD spectroscopy, excluding all but one diastereomeric structural candidates is challenging because stereochemical inversion of one chiral center...

Method screening strategies of stereoisomers of compounds with multiple chiral centers and a single chiral center

2020 ◽  
Vol 1624 ◽  
pp. 461244 ◽  
Author(s):  
Jessica Lin ◽  
Charlotte Tsang ◽  
Raymond Lieu ◽  
Kelly Zhang
Keyword(s):  
Chiral Center ◽  
Screening Strategies ◽  
Chiral Centers

scholarly journals The Assignment of the Absolute Configuration of C-22 Chiral Center in the Aglycones of Triterpene Glycosides from the Sea Cucumber Cladolabes schmeltzii and Chemical Transformations of Cladoloside C

2015 ◽  
Vol 10 (7) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Anatoly I. Kalinovsky ◽  
Alexandra S. Silchenko ◽  
Sergey A. Avilov ◽  
Vladimir I. Kalinin
Keyword(s):  
Absolute Configuration ◽  
Sea Cucumber ◽  
Triterpene Glycosides ◽  
Chiral Center ◽  
Biosynthetic Pathways ◽  
Chemical Transformations ◽  
Chemical Structures ◽  
Different Types ◽  
The Absolute ◽  
Chiral Centers

The absolute R-configuration of the C-22 chiral center in cladoloside C (1) and therefore in all related glycosides isolated from the sea cucumber Cladolabes schmeltzii has been assigned by Mosher‘s method. Some chemical transformations of the native glycoside 1 were carried out to apply this method. This resulted in the isolation and elucidation of chemical structures of progenin 2 and artefact aglycones 3 and 4, obtained from 1 and assignment of the absolute R-configuration of C-22 in the progenin 2. The coincidence of C-22 configurations in the studied compounds with those of the earlier known lanostane-type aglycone of frondoside C and holostane-type aglycone of cladoloside C (1) confirms the generic biosynthetic pathways to different types of sea cucumber glycoside aglycones. It suggests the same R-configuration of C-22 chiral centers in all the sea cucumber glycosides having C-22 functionalities.

Recent advances for the synthesis of chiral sulfones with the sulfone moiety directly connected to the chiral center

2021 ◽  
Author(s):  
Chuanle Zhu ◽  
Yingying Cai ◽  
Huanfeng Jiang
Keyword(s):  
Natural Products ◽  
Bioactive Compounds ◽  
Building Blocks ◽  
Chiral Center ◽  
Recent Advances ◽  
Chiral Centers

Chiral sulfones, especially for those compounds with the sulfone groups directly connected to the chiral centers, are privileged building blocks in many natural products and bioactive compounds. Thus, the development...

Total synthesis of 14β-hydroxy-4,9(11)- androstadiene-3,17-dione

1979 ◽  
Vol 57 (11) ◽  
pp. 1397-1398 ◽  
Author(s):  
Andrzej Robert Daniewski ◽  
Peter S. White ◽  
Zdenek Valenta
Keyword(s):  
Total Synthesis ◽  
Title Compound ◽  
Aldol Condensation ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Chiral Center ◽  
Asymmetric Induction ◽  
Methyl Vinyl ◽  
Chiral Centers

The title compound 8, a potential intermediate in the total synthesis of cardiac-active principles and other polyfunctional steroids, is prepared in nine steps using methyl vinyl ketone and 2-methylcyclohexane-1,3-dione as starting materials and acetylene and 2-methylcyclopentane-1,3-dione as additional sources of carbon atoms. In a crucial aldol condensation leading to the closure of steroid ring C, an efficient asymmetric induction by one chiral center leads to the establishment of three new chiral centers.

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

Culture and the plasticity of perception

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Lifshitz ◽  
T. M. Luhrmann
Keyword(s):  
Cultural Context ◽  
Sensory Experience ◽  
Cultural Learning ◽  
The World

Abstract Culture shapes our basic sensory experience of the world. This is particularly striking in the study of religion and psychosis, where we and others have shown that cultural context determines both the structure and content of hallucination-like events. The cultural shaping of hallucinations may provide a rich case-study for linking cultural learning with emerging prediction-based models of perception.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Sociocultural memory development research drives new directions in gadgetry science

2019 ◽  
Vol 42 ◽  
Author(s):  
Penny Van Bergen ◽  
John Sutton
Keyword(s):  
Episodic Memory ◽  
Autobiographical Memory ◽  
Developmental Psychology ◽  
Cross Cultural ◽  
Memory Development ◽  
Development Research ◽  
Cultural Research ◽  
New Directions ◽  
Cross Cultural Research

Abstract Sociocultural developmental psychology can drive new directions in gadgetry science. We use autobiographical memory, a compound capacity incorporating episodic memory, as a case study. Autobiographical memory emerges late in development, supported by interactions with parents. Intervention research highlights the causal influence of these interactions, whereas cross-cultural research demonstrates culturally determined diversity. Different patterns of inheritance are discussed.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

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