title: Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones - First evidence for the 1,3-oxathiole-thiocarbonyl ylide interconversion.
abstract: Acyclic diazodicarbonyl compounds react at room temperature with cycloaliphatic thioketones, e.g. 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one and adamantanethione, via a cascade process in which the key step is a 1,5-electrocyclization of the intermediate thiocarbonyl ylide leading to tetrasubstituted spirocyclic 1,3-oxathioles. The most reactive diazodicarbonyl compound was diazoacetylacetone. In the case of dimethyl diazomalonate competitive 1,3-electrocyclization yielded the corresponding thiirane at elevated temperature, which after spontaneous desulfurization produced a tetrasubstituted alkene. To explain the observed temperature dependence of the main reaction product type obtained from dimethyl diazomalonate and 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one as well as to verify reversibility of the thiocarbonyl ylide and 1,3-oxathiole interconversion, the calculations of the energy profile for the transformation of 1,3-oxathiole to alkene were performed at the DFT PBE1PBE/6-31G(d) level.
authors.affiliation: Saint-Petersburg State University, 198504, Saint Petersburg, University prosp., 26, Russia.
authors.forename: Valerij A
authors.initials: VA
authors.lastname: Nikolaev
authors.affiliation: Saint-Petersburg State University, 198504, Saint Petersburg, University prosp., 26, Russia.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Ivanov
authors.affiliation: Saint-Petersburg State University, 198504, Saint Petersburg, University prosp., 26, Russia.
authors.forename: Ludmila L
authors.initials: LL
authors.lastname: Rodina
authors.affiliation: University of Łódź, Faculty of Chemistry, Tamka 12, 91-403, Łódź, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Mlostoń
keywords: 1,3-dipolar electrocyclization; 1,3-oxathioles; 1,5-dipolar electrocyclization; thiiranes; thiocarbonyl ylides; thioketones