New Thiocarbonyl Ylides derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and reactions

The reaction of 3,3-dichloro-2,2,4,4-tetramethylcyclobutanethione (1) with diazo compounds yielded spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3, which decomposed at ca. 45°C to give the corresponding thiocarbonyl ylide of type 4. In the absence of trapping agents, these thiocarbonyl ylides underwent a 1,3-dipolar electrocyclization to yield spirocyclic thiiranes 5. On the other hand, the thiocarbonyl methanide 4a was efficiently intercepted with C C, C=C, C=O, C=S, and N=N dipolarophiles leading to the [2+3] cycloadducts. A non-stereoselective cycloaddition took place when 3a was decomposed in the presence of the very electron-deficient dicyanofumarate or maleate, indicating a two step mechanism via an intermediate zwitterion. Furthermore, the thiocarbonyl methanide 4a could be trapped by the imidazole-2-thione 7 to give the 1,3-adduct 8. Treatment of 3a with secondary amines led to amidrazones of type 25 via base-catalyzed ring opening and condensation reaction. DOI: https://doi.org/10.1002/chin.200706033 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-51288 Published Version Originally published at: Woznicka, M; Rutkowska, M; Mloston, G; Majchrzak, A; Heimgartner, H (2006). New Thiocarbonyl Ylides derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and reactions. Polish Journal of Chemistry, 80(10):1683-1693. DOI: https://doi.org/10.1002/chin.200706033 New Thiocarbonyl Ylides Derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and Reactions by M. WoŸnicka 1* , M. Rutkowska 1 , G. Mlostoñ 1** , A. Majchrzak 2 and H. Heimgartner 2** 1 Section of Heteroorganic Compounds, University of £ódŸ, Narutowicza 68, PL-90-136 £ódŸ, Poland 2 Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland (Received May 4th, 2006) The reaction of 3,3-dichloro-2,2,4,4-tetramethylcyclobutanethione (1) with diazo compounds yielded spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3, which decomposed at ca. 45°C to give the corresponding thiocarbonyl ylide of type 4. In the absence of trapping agents, these thiocarbonyl ylides underwent a 1,3-dipolar electrocyclization to yield spirocyclic thiiranes 5. On the other hand, the thiocarbonyl methanide 4a was efficiently intercepted with C C, C=C, C=O, C=S, and N=N dipolarophiles leading to the [2+3] cycloadducts. A non-stereoselective cycloaddition took place when 3a was decomposed in the presence of the very electron-deficient dicyanofumarate or maleate, indicating a two step mechanism via an intermediate zwitterion. Furthermore, the thiocarbonyl methanide 4a could be trapped by the imidazole-2-thione 7 to give the 1,3-adduct 8 . Treatment of 3awith secondary amines led to amidrazones of type 25 viabase-catalyzed ring opening and condensation reaction.