Header

UZH-Logo

Maintenance Infos

1,5-Dipolar electrocyclizations of Thiocarbonyl Ylides bearing C=N groups: Reactions of N-[(Dimethylamino)methylene]thiobenzamide and 2-(Dimethylhydrazono)-1-phenylethane-1-thione with Diazo compounds


Egli, D H; Linden, A; Heimgartner, H (2007). 1,5-Dipolar electrocyclizations of Thiocarbonyl Ylides bearing C=N groups: Reactions of N-[(Dimethylamino)methylene]thiobenzamide and 2-(Dimethylhydrazono)-1-phenylethane-1-thione with Diazo compounds. Helvetica Chimica Acta, 90(1):86-100.

Abstract

The reactions of thiobenzamide 8 with diazo compounds proceeded via reactive thiocarbonyl ylides as intermediates, which underwent either a 1,5-dipolar electrocyclization to give the corresponding five-membered heterocycles, i.e., 4-amino-4,5-dihydro-1,3-thiazole derivatives (i.e., 10a, 10b, 10c, cis-10d, and trans-10d) or a 1,3-dipolar electrocyclization to give the corresponding thiiranes as intermediates, which underwent a SNi’-like ring opening and subsequent 5-exo-trig cyclization to yield the isomeric 2-amino-2,5-dihydro-1,3-thiazole derivatives (i.e., 11a, 11b, 11c, cis-11d, and trans-11d). In general, isomer 10 was formed in higher yield than isomer 11. In the case of the reaction of 8 with diazo(phenyl)methane (3d), a mixture of two pairs of diastereoisomers was formed, of which two, namely cis-10d and trans-10d, could be isolated as pure compounds. The isomers cis-11d and trans-11d remained as a mixture. In the reactions of the thioxohydrazone 9 with diazo compounds 3b and 3d, the main products were
the alkenes 18 and 23, respectively. Their formation was rationalized by a 1,3-dipolar electrocyclization of the corresponding thiocarbonyl ylide and subsequent desulfurization of the intermediate thiiran. As minor products, 2,5-dihydro-1,3-thiazol-5-amines 21 and 24 were obtained, which have been formed by 1,5-dipolar electrocyclization of the thiocarbonyl ylide, followed by a 1,3-shift of the dimethylamino group.

Abstract

The reactions of thiobenzamide 8 with diazo compounds proceeded via reactive thiocarbonyl ylides as intermediates, which underwent either a 1,5-dipolar electrocyclization to give the corresponding five-membered heterocycles, i.e., 4-amino-4,5-dihydro-1,3-thiazole derivatives (i.e., 10a, 10b, 10c, cis-10d, and trans-10d) or a 1,3-dipolar electrocyclization to give the corresponding thiiranes as intermediates, which underwent a SNi’-like ring opening and subsequent 5-exo-trig cyclization to yield the isomeric 2-amino-2,5-dihydro-1,3-thiazole derivatives (i.e., 11a, 11b, 11c, cis-11d, and trans-11d). In general, isomer 10 was formed in higher yield than isomer 11. In the case of the reaction of 8 with diazo(phenyl)methane (3d), a mixture of two pairs of diastereoisomers was formed, of which two, namely cis-10d and trans-10d, could be isolated as pure compounds. The isomers cis-11d and trans-11d remained as a mixture. In the reactions of the thioxohydrazone 9 with diazo compounds 3b and 3d, the main products were
the alkenes 18 and 23, respectively. Their formation was rationalized by a 1,3-dipolar electrocyclization of the corresponding thiocarbonyl ylide and subsequent desulfurization of the intermediate thiiran. As minor products, 2,5-dihydro-1,3-thiazol-5-amines 21 and 24 were obtained, which have been formed by 1,5-dipolar electrocyclization of the thiocarbonyl ylide, followed by a 1,3-shift of the dimethylamino group.

Statistics

Citations

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

Altmetrics

Downloads

82 downloads since deposited on 08 Nov 2011
8 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:2007
Deposited On:08 Nov 2011 10:26
Last Modified:05 Apr 2016 15:04
Publisher:Verlag Helvetica Chimica Acta
ISSN:0018-019X
Funders:Swiss National Science Foundation , F. Hoffmann-La Roche AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.200790025

Download