Can the presence of chemically inert species modify the face selectivity in asymmetric induction by cyclodextrins?

1995 ◽  
Vol 23 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Andr� Deratani ◽  
Thierry Maraldo ◽  
Estelle Renard
Keyword(s):  
Asymmetric Induction ◽  
The Face ◽  
Face Selectivity

Asymmetric induction in Diels–Alder reactions of α-alkoxyorthoquinodimethanes

1989 ◽  
Vol 67 (6) ◽  
pp. 1010-1014 ◽  
Author(s):  
James L. Charlton ◽  
Guy L. Plourde ◽  
Glenn H. Penner
Keyword(s):  
Molecular Orbital ◽  
Geometry Optimization ◽  
Diels Alder ◽  
Asymmetric Induction ◽  
Molecular Orbital Calculations ◽  
Cycloaddition Reactions ◽  
Vinyl Ethers ◽  
The Face ◽  
Face Selectivity ◽  
Alkoxy Groups

It has been shown that dienophiles cycloadd selectively to one face of o-quinodimethanes (o-QDMs) bearing chiral α-alkoxy groups. The face selectivity (diastereoselectivity) increases for the series of chiral groups -OCH(Ph)CH3, -OCH(Ph)CH(CH3)2, and -OCH(Ph)C(CH3)3. A similar effect on the face selectivity of the Diels–Alder reactions of chiral alkoxy vinyl ethers for the same series of chiral groups has been noted previously by others. A mechanism has been proposed to explain the face selectivity in the cycloaddition reactions of the alkoxy o-QDMs. Abinitio molecular orbital calculations with geometry optimization on vinyl 1-phenylethyl ether to determine its lowest energy conformations support the proposed mechanism. The absolute stereochemistries of the o-QDM cycloadducts have been determined to verify the predictions of the model. Keywords: o-quinodimethanes, asymmetric, Diels–Alder, cycloaddition.

Search for nucleophilicity effect on the face selectivity of addition to a sterically unbiased ketone

1988 ◽  
Vol 53 (21) ◽  
pp. 5155-5158 ◽  
Author(s):  
M. H. Lin ◽  
J. E. Silver ◽  
W. J. Le Noble
Keyword(s):  
The Face ◽  
Face Selectivity

Stereochemical Characterisation of the Non-Canonical α-Humulene Synthase from Acremonium strictum

2021 ◽  
Author(s):  
Houchao Xu ◽  
Carsten Schotte ◽  
Russell Cox ◽  
Jeroen Dickschat
Keyword(s):  
Isotopic Labelling ◽  
Acremonium Strictum ◽  
The Face ◽  
Face Selectivity ◽  
Isotopic Labelling Experiments

The non-canonical fungal α-humulene synthase was investigated through isotopic labelling experiments for its stereochemical course regarding inversion or retention at C-1, the face selectivity at C-11, and the stereoselectivity of...

Effect of allylic substituents on the face selectivity of Diels-Alder reactions of semicyclic dienes

1990 ◽  
Vol 112 (23) ◽  
pp. 8472-8478 ◽  
Author(s):  
S. C. Datta ◽  
R. W. Franck ◽  
R. Tripathy ◽  
G. J. Quigley ◽  
L. Huang ◽  
...  
Keyword(s):  
Diels Alder ◽  
The Face ◽  
Face Selectivity

The face selectivity directed by an allylic group of a diene in the diels-alder reaction is reversed from that of a dienophile

1985 ◽  
Vol 26 (27) ◽  
pp. 3187-3190 ◽  
Author(s):  
Richard W. Franck ◽  
S. Argade ◽  
C.S. Subramaniam ◽  
Denise M. Frechet
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
The Face ◽  
Face Selectivity

scholarly journals Comparing Face and Object Processing in Perception and Recognition

2021 ◽  
Author(s):  
Narjes Soltani Dehaghani ◽  
◽  
Burkhard Maess ◽  
Reza Khosrowabadi ◽  
Mojtaba Zarei ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Face Processing ◽  
Peak Time ◽  
Levels Of Processing ◽  
Object Processing ◽  
Amount Of Information ◽  
Facial Processing ◽  
The Face ◽  
Face Selectivity ◽  
Human Faces

Faces can be speedily processed, although they convey an immense amount of information. Hence, in psychophysiological experiments, human faces constitute very special stimuli! Numerous studies have investigated the electrophysiological correlates of face processing, showing the existence of multiple event-related components. Nevertheless, dissimilarities in various levels of processing are still controversial. In this present study, we used magnetoencephalography (MEG) to examine how facial processing is different in perception and recognition from object processing and also determined 95% confidence interval for the onset and peak time of the effects we found. Our results confirm the face-selectivity for the M170 component, but not always for the M100 component. Additionally, we observed a unique speed pattern for the M170 component in perception and recognition both at the onset and the peak time.

scholarly journals The Retrieval-related Anterior shift is Moderated by Age and Correlates with Memory Performance

2021 ◽  
Author(s):  
Sabina Srokova ◽  
Paul F Hill ◽  
Michael D Rugg
Keyword(s):  
Neural Activity ◽  
Human Subjects ◽  
Memory Performance ◽  
Age Groups ◽  
Memory Decline ◽  
Individual Participant ◽  
The Face ◽  
Face Selectivity ◽  
With Memory ◽  
Encoding And Retrieval

Recent research suggests that episodic memory is associated with systematic differences in the localization of neural activity observed during memory encoding and retrieval. The retrieval-related anterior shift is a phenomenon whereby the retrieval of a stimulus event (e.g., a scene image) is associated with a peak neural response which is localized more anteriorly than the response elicited when the stimulus is experienced directly. Here, we examine whether the magnitude of the anterior shift, i.e., the distance between encoding- and retrieval-related response peaks, is moderated by age, and also whether the shift is associated with memory performance. Younger and older human subjects of both sexes underwent fMRI as they completed encoding and retrieval tasks on word-face and word-scene pairs. We localized peak scene- and face-selectivity for each individual participant within the face-selective precuneus (PCU) and in three scene-selective (parahippocampal place area [PPA], medial place area [MPA], occipital place area [OPA]) regions of interest (ROIs). In line with recent findings, we identified an anterior shift in PPA and OPA in both age groups and, in older adults only, in MPA and PCU also. Of importance, the magnitude of the anterior shift was larger in older than in younger adults. The shift within the PPA exhibited an age-invariant across-participant negative correlation with source memory performance, such that a smaller displacement between encoding- and retrieval-related neural activity was associated with better performance. These findings provide novel insights into the functional significance of the anterior shift, especially in relation to memory decline in older age.

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