scholarly journals Stereoselective Nanocarbon Imides Featuring 12-fold [5]helicenes

2022 ◽  
Author(s):  
Guogang Liu ◽  
Marvin Nyenhuis ◽  
Dong Meng ◽  
Nikos L. Doltsinis ◽  
Yan Li ◽  
...  
Keyword(s):  
Bond Formation ◽  
Cd Spectroscopy ◽  
Chiral Hplc ◽  
Chiroptical Properties ◽  
Great Progress ◽  
Inside Out ◽  
Rigid Skeleton

Despite the great progress in research on chiral molecular nanocarbons containing multiple helicenes, controlling the stereoselectivity is still a major challenge, especially when attempting to increase the number of helicene moieties. Herein, a novel molecular nanocarbon imides composed of C204 skeleton and eighteen imide groups was successfully synthesized via an inside–out ring closing strategy involving repeated Suzuki–Miyaura coupling for C–C bond formation and photocyclic aromatization. Because of the presence of quad–core twelvefold [5]helicenes, there are, in theory, more than one hundred stereoisomers. However, only one pair of stereoisomers with D3 symmetry was observed. Despite the large and rigid skeleton, the (3M,3M,3M,3M)+(3P,3P,3P,3P) enantiomers were successfully separated by chiral HPLC, and the chiroptical properties were investigated by CD spectroscopy.

Asymmetric C-H and N-H functionalization of Indoles involving Central Chirality via Chiral Phosphoric Acid Catalysis

2021 ◽  
Vol 18 ◽  
Author(s):  
Alemayehu Gashaw ◽  
Dereje Kebebew Debeli ◽  
Meseret Chemeda
Keyword(s):  
Phosphoric Acid ◽  
Organic Compounds ◽  
Organic Synthesis ◽  
Acid Catalysis ◽  
Bond Formation ◽  
Acid Catalysts ◽  
Asymmetric Syntheses ◽  
Chiral Phosphoric Acid ◽  
Great Progress ◽  
Interesting Area

: The C-H and N-H functionalization of indoles is an interesting area of research that has a useful impact on organic synthesis due to the availability of chiral indole scaffolds in the discovery of drugs, synthetic bioactive compounds, and natural products. The chiral phosphoric acid catalysts (CPAs) have proven to be a powerful and versatile class of enantioselective organocatalysts. Many asymmetric syntheses of organic compounds have been carried out with these catalysts in C–C and C-N bond formation reactions, and great progress has been reported. By 2011, several reviews were published covering some important topics and recent achievements in this field. Therefore, in this review, the most recent advances, research breakthroughs with key examples involving mechanisms of CPA-catalyzed C-H and N-H functionalization of indoles to form central chirality via Friedel Crafts, Michael type, and rearrangement reactions were reviewed and reported.

Synthesis and chiroptical properties of heterodetic cyclic hexapeptides related to oxytocin ring moiety

1980 ◽  
Vol 45 (4) ◽  
pp. 1109-1131 ◽  
Author(s):  
Ivo Frič ◽  
Lyudmila I. Leonteva ◽  
Petr Maloň ◽  
Karel Jošt ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Peptide Synthesis ◽  
Spatial Arrangement ◽  
Cd Spectroscopy ◽  
Side Chains ◽  
Peptide Backbone ◽  
Chiroptical Properties ◽  
Disulfide Group ◽  
Cyclic Hexapeptides

Cyclic disulfides of cysteinyl-tetraglycyl-cysteine (Ia), cysteinyl-tyrosyl-triglycyl-cysteine (Ib) and cysteinyl-tyrosyl-isoleucyl-diglycyl-cysteine (Ic) were synthesized by classical methods of peptide synthesis. The actions of solvent and of side chains in the positions 2 and 3 on the conformational arrangement of the peptide backbone and the disulfide group were investigated by means of CD spectroscopy. Some mechanisms which co-operate in stabilizing the oxytocin conformation were identified. Hence, it may be deduced, that the amino acid sequence in the positions 1-3 determines the spatial arrangement characteristic for oxytocin, at least in a protonating medium.

Resolution by chiral hplc of the stable free radical perchlorotriphenylmethyl: Thermodynamic and chiroptical properties

Chirality ◽  
1995 ◽  
Vol 7 (3) ◽  
pp. 154-157 ◽  
Author(s):  
José Irurre ◽  
Jesüs Santamaría ◽  
M. Concepción González-rego
Keyword(s):  
Free Radical ◽  
Chiral Hplc ◽  
Stable Free Radical ◽  
Chiroptical Properties ◽  
Resolution By Chiral Hplc

scholarly journals Synthesis of a Möbius carbon nanobelt

2021 ◽  
Author(s):  
Kenichiro Itami ◽  
Yasutomo Segawa ◽  
Tsugunori Watanabe ◽  
Kotono Yamanoue ◽  
Motonobu Kuwayama ◽  
...  
Keyword(s):  
Carbon Nanostructures ◽  
New Technologies ◽  
Materials Science ◽  
Theoretical Calculations ◽  
Cd Spectroscopy ◽  
Chiral Hplc ◽  
Repeat Units ◽  
Isolation And Characterization ◽  
Möbius Structure

New technologies for the creation of topological carbon nanostructures have significantly advanced synthetic organic chemistry and materials science. While simple molecular nanocarbons with a belt topology have been constructed recently, analogous carbon nanobelts with a twist, i.e., Möbius carbon nanobelts (MCNBs), have not yet been synthesized due to their high intrinsic strain. Herein, we report the synthesis, isolation, and characterization of a MCNB. Calculations of strain energies suggested that large MCNBs are synthetically accessible. Designing a macrocyclic precursor with an odd number of repeat units led to a successful rational synthetic route via Z-selective Wittig reactions and nickel-mediated intramolecular homocoupling reactions, which yielded (25,25)MCNB over 14 steps. NMR and theoretical calculations revealed that the twist moiety of the Möbius band moves quickly around the MCNB molecule in solution. The topological chirality originating from the Möbius structure was confirmed experimentally using chiral HPLC separation and CD spectroscopy.

Directly Coupled Chiral HPLC−NMR and HPLC−CD Spectroscopy as Complementary Methods for Structural and Enantiomeric Isomer Identification:  Application to Atracurium Besylate

1999 ◽  
Vol 71 (14) ◽  
pp. 2838-2843 ◽  
Author(s):  
Nisha Mistry ◽  
Andrew D. Roberts ◽  
George E. Tranter ◽  
Peter Francis ◽  
Ian Barylski ◽  
...  
Keyword(s):  
Cd Spectroscopy ◽  
Chiral Hplc ◽  
Complementary Methods

The Structure Among Measures of Personality, Social Attitudes, Values, and Social Norms

2007 ◽  
Vol 28 (4) ◽  
pp. 240-251 ◽  
Author(s):  
Lazar Stankov
Keyword(s):  
Factor Analysis ◽  
Individual Differences ◽  
Social Norms ◽  
Social Interactions ◽  
Correlation Matrix ◽  
Social Attitudes ◽  
Group Differences ◽  
Factor Scores ◽  
Ethnic Group Differences ◽  
Inside Out

Abstract. This paper presents the results of a study that employed measures of personality, social attitudes, values, and social norms that have been the focus of recent research in individual differences. These measures were given to a sample of participants (N = 1,255) who were enrolled at 25 US colleges and universities. Factor analysis of the correlation matrix produced four factors. Three of these factors corresponded to the domains of Personality/Amoral Social Attitudes, Values, and Social Norms; one factor, Conservatism, cut across the domains. Cognitive ability showed negative correlation with conservatism and amoral social attitudes. The study also examined gender and ethnic group differences on factor scores. The overall interpretation of the findings is consistent with the inside-out view of human social interactions.

Origin of Mind: Outside-In or Inside-Out?

1986 ◽  
Vol 31 (7) ◽  
pp. 529-530
Author(s):  
Diane Poulin-Dubois
Keyword(s):  
Origin Of Mind ◽  
Inside Out
Sign in / Sign up

Export Citation Format

Share Document