Header

UZH-Logo

Maintenance Infos

Synthesis and characterization of new Heptalenes with extended π-systems attached to them


Maillefer-El Houar, Sarah; Uebelhart, Peter; Linden, Anthony; Hansen, Hans-Jürgen (2013). Synthesis and characterization of new Heptalenes with extended π-systems attached to them. Helvetica Chimica Acta, 96(8):1488-1541.

Abstract

Methyl heptalenecarboxylates of type A and B with π(1) and π(2) substituents in 1,4-relation (Scheme 1) were synthetized starting with dimethyl 1-methylheptalene-4,5-dicarboxylates 5b and 6b derived from 7-isopropyl-1,4-dimethylazulene (=guaiazulene) and 1,4,6,8-tetramethylazulene by thermal reaction with dimethyl acetylenedicarboxylate. The further general way of proceeding for the introduction of the π(1) and π(2) substituents is displayed in Scheme 3, and the thus obtained methyl heptalene-5-carboxylates of type A and B are listed in Table 1. The C[DOUBLE BOND]C bonds of the 2-arylethenyl and 4-arylbuta-1,3-dien-1-yl groups of π(1) and π(2) were in all cases (E)-configured and showed s-trans conformation at the C[BOND]C bonds (X-ray and 1H-NOE evidence) in the B-type as well as in the A-type heptalenes (cf. Figs. 5–12).
All B-type heptalenes showed a strongly enhanced heptalene band I in the wavelength region 440–490 nm in hexane/CH2Cl2 9 : 1 (cf. Table 4 and Figs. 13–20). The A-type heptalenes showed in this region only weak absorption, recognizable as shoulders or simply tailing of the dominating heptalene bands II/III (Table 5). Absorption band I of the B-type heptalenes appeared almost at the same wavelength as the longest wavelength absorption band of comparable open-chain α,ω-diarylpolyenes (cf. Fig. 21). The cyclic double bond shift (DBS) of the A- and B-type heptalenes could be photochemically steered in one or the other direction by selective irradiation (cf. Fig. 22).

Abstract

Methyl heptalenecarboxylates of type A and B with π(1) and π(2) substituents in 1,4-relation (Scheme 1) were synthetized starting with dimethyl 1-methylheptalene-4,5-dicarboxylates 5b and 6b derived from 7-isopropyl-1,4-dimethylazulene (=guaiazulene) and 1,4,6,8-tetramethylazulene by thermal reaction with dimethyl acetylenedicarboxylate. The further general way of proceeding for the introduction of the π(1) and π(2) substituents is displayed in Scheme 3, and the thus obtained methyl heptalene-5-carboxylates of type A and B are listed in Table 1. The C[DOUBLE BOND]C bonds of the 2-arylethenyl and 4-arylbuta-1,3-dien-1-yl groups of π(1) and π(2) were in all cases (E)-configured and showed s-trans conformation at the C[BOND]C bonds (X-ray and 1H-NOE evidence) in the B-type as well as in the A-type heptalenes (cf. Figs. 5–12).
All B-type heptalenes showed a strongly enhanced heptalene band I in the wavelength region 440–490 nm in hexane/CH2Cl2 9 : 1 (cf. Table 4 and Figs. 13–20). The A-type heptalenes showed in this region only weak absorption, recognizable as shoulders or simply tailing of the dominating heptalene bands II/III (Table 5). Absorption band I of the B-type heptalenes appeared almost at the same wavelength as the longest wavelength absorption band of comparable open-chain α,ω-diarylpolyenes (cf. Fig. 21). The cyclic double bond shift (DBS) of the A- and B-type heptalenes could be photochemically steered in one or the other direction by selective irradiation (cf. Fig. 22).

Statistics

Citations

2 citations in Web of Science®
3 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

1 download since deposited on 21 Oct 2013
0 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2013
Deposited On:21 Oct 2013 08:51
Last Modified:05 Apr 2016 17:03
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Swiss National Science Foundation
Publisher DOI:https://doi.org/10.1002/hlca.201300137

Download