A copper-mediated procedure for terminal alkynyl-propargyl coupling has been applied to "skipped" bis-terminal undecatetrayne and 1,4-bis(pseudo)halobut-2-ynes with the aim of preparing ring carbomers of representative strained and loose cycloalkanes, namely [N]pericyclynes. Two unprecedented, cyclic. "skipped" polyynes with CH2 vertices have been isolated as mixtures of diastereoisomers: an isomer 1b and a dimer 2a of [5]pericyclyne 1a. The isomer 1b is a cyclotetrayne with an exocyclic allene function resulting from a unique formal SN process. Its structure has been established by 1H/13C HMQC and HMBC two-dimensional NMR analysis. According to density functional theory calculations, it is about 6 kcalmol(-1) more stable than [5]pericyclyne (1a). Compound 1b can also be regarded as a C13-relaxed [4]pericyclyne, a long sought "skipped" C12 tetrayne. The dimer 2a is a C30 ring that results from a formal SN process. It is a stable ring carbomer of cyclodecane, that is, a [10]pericyclyne, with four CH2 vertices.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/1521-3765(20010316)7:6<1165::aid-chem1165>3.0.co;2-3 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
From Stilbenes to carbo-Stilbenes: an Encouraging Prospect.
Chemistry
May 2024
Faculté Science et Ingénierie - Département de Chimie., Unsaturated molecules for physics, biology and chemistry group., Université Toulouse III - Paul Sabatier, 118 route de Narbonne, 31-062, Toulouse Cedex 09, France.
Beyond previously described carbo-naphthalene and carbo-biphenyl, a novel type of bis-carbo-benzenic molecules is envisaged from the stilbene parent. The synthesis, structure, spectroscopic and electrochemical properties of two such carbo-stilbenes are described at complementary experimental and computational DFT levels. In the selected targets, the bare skeletal carbo-mer of carbo-stilbene is decorated by 8 or 10 phenyl groups, 0 or 2 tert-butyl groups, and 2 n-octyl chains, the later substituents being introduced to compensate anticipated solubility issues.
View Article and Find Full Text PDFThe effects of pediatric dentifrices with different types of fluoride on the color change of restorative materials.
Eur Oral Res
January 2022
Department of Pediatric Dentistry, Faculty of Dentistry, Istanbul Okan University, IstanbulTurkey.
Purpose: This study aimed to evaluate the effects of dentifrices with different fluoride content on color change of restorative materials commonly used in pediatric dentistry.
Materials And Methods: Three restorative materials (glass hybrid [Equia Forte (EF)], glass carbomer [GCP Glass Fill (GCP)] and compomer [Dyract XP (DXP)]) were used to prepare 120 disc shaped specimens by using a Teflon ring. Four dentifrice groups were created as Sodium Fluoride (NaF), Amine Fluoride (AmF), Stannous Fluoride (SnF2) and no-fluoride (n=40).
Core carbo-mer of an Extended Tetrathiafulvalene: Redox-Controlled Reversible Conversion to a carbo-Benzenic Dication.
Chemistry
August 2020
LCC-CNRS, Université de Toulouse, CNRS, UPS, Toulouse, France.
carbo-Benzene is an aromatic molecule devised by inserting C units within each C-C bond of the benzene molecule. By integrating the corresponding carbo-quinoid core as bridging unit in a π-extended tetrathiafulvalene (exTTF), it is shown that a carbo-benzene ring can be reversibly formed by electrochemical reduction or oxidation. The so-called carbo-exTTF molecule was thus experimentally prepared and studied by UV-visible absorption spectroscopy and cyclic voltammetry, as well as by X-ray crystallography and by scanning tunneling microscopy (STM) on a surface of highly oriented pyrolytic graphite (HOPG).
View Article and Find Full Text PDFCarbo-biphenyls and Carbo-terphenyls: Oligo(phenylene ethynylene) Ring Carbo-mers.
Angew Chem Int Ed Engl
May 2018
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.
Ring carbo-mers of oligo(phenylene ethynylene)s (OPEn, n=0-2), made of C -catenated C carbo-benzene rings, have been synthesized and characterized by NMR and UV-vis spectroscopy, crystallography and voltammetry. Analyses of crystal and DFT-optimized structures show that the C rings preserve their individual aromatic character according to structural and magnetic criteria (NICS indices). Carbo-terphenyls (n=2) are reversibly reduced at ca.
View Article and Find Full Text PDFcarbo-Naphthalene: A Polycyclic carbo-Benzenoid Fragment of α-Graphyne.
Angew Chem Int Ed Engl
November 2016
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.
A ring carbo-mer of naphthalene, C Ar (Ar=p-n-pentylphenyl), has been obtained as a stable blue chromophore, after a 19-step synthetic route involving methods inspired from those used in the synthesis of carbo-benzenes, or specifically devised for the present target, like a double Sonogashira-type coupling reaction. The last step is a SnCl /HCl-mediated reduction of a decaoxy-carbo-decalin, which is prepared through successive [8+10] macrocyclization steps. Two carbo-benzene references are also described, C Ar and o-C Ar (C≡C-SiiPr ) .
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!