Problems with a conformation assignment of aryl-substituted resorc[4]arenes

[img]PDF - Authorized users only
Language: English
1480Kb
Title:Problems with a conformation assignment of aryl-substituted resorc[4]arenes
Creators:
Kaminský, Jakub
Dvořáková, Hana
Štursa, Jan
Moravcová, Jitka
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 76, 10, pp. 1199-1222
Uncontrolled Keywords:Density functional theory, NOE, Conformational analysis, Aryl-substituted resorc[4]arenes

Abstract

Acid-catalyzed condensation of resorcinol with 3,5-diisopropoxybenzaldehyde and 3,5-dihydroxybenzaldehyde afforded aryl substituted resorc[4]arenes <b>1a</b> and <b>1b</b>, respectively. All 16 hydroxyls in <b>1b</b> were acetylated providing resorc[4]arene <b>1c</b>. The conformational behaviour of <b>1a</b>, <b>1b</b> and <b>1c</b> was studied by NMR spectroscopy and quantum chemical calculations. It was found that the stabilization of their conformations is an effect of competing π-π and OH-π interactions, hydrogen bonding and steric features, respectively. As a result, <i>C</i><sub>2</sub> symmetrical <i>boat</i> conformations <b>1a</b>, <b>1b</b> and <b>1c</b> with aryls in axial positions were identified in all cases. In case of <b>1c</b> also the formation of <i>C</i><sub>2</sub> symmetrical conformation with aryls in equatorial positions (<i>boat</i>-<i>eq</i>) was identified. Moreover, compounds <b>1a</b> and <b>1b</b> being able to create hydrogen bonds, adopt also symmetrical <i>C</i><sub>4</sub> <i>crown</i> conformations. For <b>1c</b>(<i>boat</i>-<i>ax</i>), the <i>boat</i>-<i>boat</i> conversion with energy barrier of 80 kJ/mol was observed, while the <i>1c</i>(<i>boat</i>-<i>eq</i>) was found to be rigid in the whole accessible temperature range. Both conformers of <b>1c</b> exhibit also second dynamic process – rotation of bridge aryl rings (Δ<i>G</i>‡ = 66 kJ/mol).

Title:Problems with a conformation assignment of aryl-substituted resorc[4]arenes
Creators:
Kaminský, Jakub
Dvořáková, Hana
Štursa, Jan
Moravcová, Jitka
Uncontrolled Keywords:Density functional theory, NOE, Conformational analysis, Aryl-substituted resorc[4]arenes
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:76
Number:10
Page Range:pp. 1199-1222
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc2010104UNSPECIFIED
ID Code:6830
Item Type:Article
Deposited On:01 Nov 2011 12:27
Last Modified:01 Nov 2011 11:27

Citation

Kaminský, Jakub; Dvořáková, Hana; Štursa, Jan; Moravcová, Jitka (2011) Problems with a conformation assignment of aryl-substituted resorc[4]arenes. Collection of Czechoslovak Chemical Communications, 76 (10). pp. 1199-1222.

Repository Staff Only: item control page