Versatile Reactivity of Phosphagermaallene Tip(t‑Bu)GeCPMes with α‑Ethylenic Esters

• Published in: Organometallics Vol. 32; no. 4; pp. 1085 - 1093
• Main Authors: Ghereg, Dumitru, Ouhsaine, Fatima, Escudié, Jean, Labat, Stéphane, André, Erwan, Miqueu, Karinne, Sotiropoulos, Jean-Marc, Gornitzka, Heinz, Saffon, Nathalie
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 25.02.2013; Amer Chemical Soc
• Subjects: Chemical Sciences; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Coordination chemistry; or physical chemistry; Organic chemistry; Physical Sciences; Science & Technology; Theoretical and; 1,3-DIPOLE BEHAVIOR; 1-SILAALLENE; GROUP-14
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om301224t

The phosphagermaallene Tip(t-Bu)GeCPMes* (1) (Tip = 2,4,6-triisopropylphenyl, Mes* = 2,4,6-tri-tert-butylphenyl) reacts with methyl crotonate, methyl cinnamate, and methyl fumarate according to a [2+2] cycloaddition between the GeC and CO double bonds to afford oxagermacyclobutanes 2–4. With methyl maleate, a [2+4] cycloaddition is observed between the GeC double bond and the OC–CC moiety, leading to oxagermacyclohexene 5. With methyl acrylate, phosphagermaallene 1 behaves as a 1,3-dipole, giving a transient five-membered-ring germa(phosphino)carbene, which rearranges by insertion of the carbenic carbon atom into a CH bond of a tert-butyl group of the Mes* group to afford the tricyclic derivative 8. These results have been supported by a theoretical approach in order to describe the reaction pathways and explain the different experimental results.