scholarly journals Chiroptical molecular propellers based on hexakis(phenylethynyl)benzene through the complexation-induced intramolecular transmission of local point chirality

2014 ◽  
Vol 12 (47) ◽  
pp. 9532-9538 ◽  
Author(s):  
Ryo Katoono ◽  
Keiichi Kusaka ◽  
Shunsuke Kawai ◽  
Yuki Tanaka ◽  
Keisuke Hanada ◽  
...  
Keyword(s):  
Amide Group ◽  
Benzene Derivatives ◽  
Tertiary Amide ◽  
Local Point

We designed hexakis(phenylethynyl)benzene derivatives with a tertiary amide group on each blade to achieve a helically biased propeller arrangement.

Effects of Internal Hydrogen Bonds between Amide Groups: Protonation of Alicyclic Diamides

2003 ◽  
Vol 9 (2) ◽  
pp. 81-95 ◽  
Author(s):  
Matthias Witt ◽  
Dirk Kreft ◽  
Hans-Friedrich Grützmacher
Keyword(s):  
Hydrogen Bonds ◽  
Major Part ◽  
Kinetic Method ◽  
Amide Group ◽  
Boat Conformation ◽  
Free Rotation ◽  
Tertiary Amide ◽  
Dipole Interactions ◽  
Amide Derivatives ◽  
Entropy Effects

The proton affinity ( PA) of cyclopentane carboxamide 1, cyclohexane carboxamide 2 and their secondary and tertiary amide derivatives S1, S2, T1 and T2, was determined by the thermokinetic method and the kinetic method [ PA(1) = 888 ± 5 kJ mol−1; PA(2) = 892 ± 5 kJ mol−1; PA(S1) = 920 ± 6 kJ mol−1; PA(S2) = 920 ± 6 kJ mol−1; PA(T1) = 938 ± 6 kJ mol−1; PA(T2) = 938 ± 6 kJ mol−1]. Special entropy effects are not observed. Additionally, the effects of protonation have been studied using an advanced kinetic method for all isomers 3–7 of cyclopentane dicarboxamides and cyclohexane dicarboxamides (with the exception of cis-cyclopentane-1,2-dicarboxamide) and their bis-tertiary derivatives T3–T7 by estimating the PA and the apparent entropy of protonation Δ(Δ Sapp). Finally, the study was extended to bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxamide 8 and its bis-tertiary derivative T8, to all stereoisomers of bicyclo[2.2.1]heptane-2,3-dicarboxamide 9, their secondary and tertiary amide derivatives S9 and T9, and to endo–endo–bicyclo[2.2.1]heptane-2,5-dicarboxamide 10 and the corresponding secondary and tertiary derivatives S10 and T10. Compared with 1 and 2, all alicyclic diamides exhibit a significant increase of the PA (ΔPA) and special entropy effects on protonation. For alicyclic diamides, which can not accommodate a conformation appropriate for building a proton bridge, the values of Δ PA and Δ(Δ Sapp) are small to moderate. This is explained by ion / dipole interactions between the protonated and neutral amide group which stabilize the protonated species but hinder the free rotation of the amide groups. If any of the conformations of the alicyclic diamide allows formation of a proton bridge, Δ PA and Δ(Δ Sapp) increase considerably. A spectacular case is cis-cyclohexane-1,4-dicarboxamide 7c which is the most basic monocyclic diamide, although generation of the proton bridge requires the unfavorable boat conformation with both amide substituents at a flagpole position. A pre-orientation of the two amide groups in such a 1,4-position in 10 results in a particularly large PA of < 1000 kJ mol−1. The observation of comparable values for Δ(Δ Sapp) for linear and monocyclic diamides indicates that a major part of the entropy effects originates from freezing the free rotation of the amide groups by formation of the proton bridge. This is corroborated by observing corresponding effects during the protonation of dicarboxamides containing the rigid bicyclo[2.2.1]heptane carbon skeleton, where the only internal movements of the molecules corresponds to rotation of the amide substituents.

scholarly journals A Comprehensive Extraction Study Using a Mono-alkylated Diglycolamic Acid Extractant: Comparison Between a Secondary Amide Group and a Tertiary Amide Group

2017 ◽  
Vol 24 (2) ◽  
pp. 61-69 ◽  
Author(s):  
Tsuyoshi SUGITA ◽  
Iori FUJIWARA ◽  
Hiroyuki OKAMURA ◽  
Tatsuya OSHIMA ◽  
Yoshinari BABA ◽  
...  
Keyword(s):  
Amide Group ◽  
Secondary Amide ◽  
Tertiary Amide ◽  
Extraction Study ◽  
Acid Extractant

Self-Assembly of Stereoisomers ofp-tert-Butyl Thiacalix[4]arenes Tetrasubstituted at the Lower Rim by a Tertiary Amide Group with Cations of p-and d-Elements in the Organic Phase

2009 ◽  
Vol 113 (36) ◽  
pp. 15838-15844 ◽  
Author(s):  
Ivan I. Stoikov ◽  
Elena A. Yushkova ◽  
Anastas A. Bukharaev ◽  
Dmitry A. Biziaev ◽  
Sufia A. Ziganshina ◽  
...  
Keyword(s):  
Organic Phase ◽  
Self Assembly ◽  
Amide Group ◽  
Tert Butyl ◽  
Tertiary Amide

Directed ortho Metalation Studies on Podocarpic Acid Derivatives: Advantageous Use of a LICKOR Base

1991 ◽  
Vol 44 (10) ◽  
pp. 1465 ◽  
Author(s):  
RC Cambie ◽  
PI Higgs ◽  
KC Lee ◽  
MR Metzler ◽  
PS Rutledge ◽  
...  
Keyword(s):  
Amide Group ◽  
Dynamic Features ◽  
Tertiary Amide ◽  
Ortho Metalation ◽  
Derivatives Of ◽  
Oxazoline Derivatives

Methyl 13-(N,N- diethylcarbamoyl )-12-methoxypodocarpa-8,11,13-trien-19-oate (2), 13-(N,N- diethylcarbamoyl )-12,19-dimethoxypodocarpa-8,11,13-triene (8) and N,N-diethyl-2-methoxy-4,5-dimethylbenzamide (15) were prepared for studies involving lithiation directed ortho to the tertiary amide group, in which the use of a LICKOR base was advantageous. Some dynamic features of the n.m.r. spectra of the amides are discussed. Oxazoline derivatives of both tile monocyclic and diterpenoid compounds were synthesized.

An alternative route to Nα-methylamino acid derivatives: Synthesis and conformation of some Nα-acetyl-Nα-methylamino acid methylamides

1988 ◽  
Vol 53 (11) ◽  
pp. 2473-2494 ◽  
Author(s):  
Jan Hlaváček ◽  
Ivo Frič ◽  
Miloš Buděšínský ◽  
Karel Bláha
Keyword(s):  
Circular Dichroism ◽  
Solvent Molecule ◽  
Amide Group ◽  
Solution Conformation ◽  
Isopropyl Esters ◽  
Tertiary Amide ◽  
Protic Solvents ◽  
Circular Dichroïsm ◽  
High Band ◽  
C Nmr

The methylation of tert-butyl- or isopropyl- esters of Nα-4-toluenesulfonyl-amino acids by dimethylsulfate in aqueous alkaline solution in the presence of a detergent gives the corresponding Nα-methylderivatives. Using this synthetic route the Nα-acetylderivatives of MeAla, MeLeu, MeOrn and MePhe methylamides have been prepared and the solution conformation of these dipeptide units has been investigated. 1H and 13C NMR spectra show that, while in dimethylsulfoxide the tertiary amide group is mostly in cis-conformation, in protic solvents the equilibrium is shifted towards trans-conformation. Circular dichroism spectra reveal some specific features (e.g. high band intensities in protic solvents) which cannot be explained solely on the basis of the increased rigidity caused by the Nα-methyl group. We tried to explain these effects supposing that the tertiary amide group is deviated from the planar arrangement (due to the interaction between the methyl groups, a substituent on Cα and a solvent molecule attached to the oxygen atom) and contributes to the observed circular dichroism as the inherently chiral chromophore.

Coefficients of molecular homeomorphism and crystalline isomorphism in the series of para-disubstituted benzene derivatives

1991 ◽  
Vol 88 ◽  
pp. 509-514 ◽  
Author(s):  
MA Cuevas Diarte ◽  
T Calvet ◽  
M Labrador ◽  
E Estop ◽  
HAJ Oonk ◽  
...  
Keyword(s):  
Benzene Derivatives ◽  
Disubstituted Benzene

Arene Dearomatization via Radical Hydroarylation

2019 ◽  
Author(s):  
Autumn Flynn ◽  
Kelly McDaniel ◽  
Meredith Hughes ◽  
David Vogt ◽  
Nathan Jui
Keyword(s):  
Precious Metal ◽  
Room Temperature ◽  
Aryl Halide ◽  
Solvent System ◽  
Benzene Derivatives ◽  
Green Solvent ◽  
Photocatalytic System

A photocatalytic system for the dearomative hydroarylation of benzene derivatives has been developed. Using a combination of an organic photoredox catalyst and an amine reductant, this process operates through a reductive radical-polar crossover mechanism where aryl halide reduction triggers a regioselective cyclization event, giving rise to a range of complex spirocyclic cyclohexadienes. This light-driven protocol functions at room temperature in a green solvent system (aq. MeCN), without the need for precious metal-based catalysts or reagents, or the generation of stoichiometric metal byproducts.

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