Reactions of Germenes with Some para-Quinones: Formation of a Tricyclic Compound from 1,4-Benzoquinone Undergoing an Unexpected Rearrangement

• Published in: Organometallics Vol. 29; no. 21; pp. 4849 - 4857
• Main Authors: Ghereg, Dumitru, André, Erwan, Ech-Cherif El Kettani, Sakina, Saffon, Nathalie, Lazraq, Mohamed, Ranaivonjatovo, Henri, Gornitzka, Heinz, Miqueu, Karinne, Sotiropoulos, Jean-Marc, Escudié, Jean
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 08.11.2010; Amer Chemical Soc
• Subjects: Catalysis; Chemical Sciences; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Coordination chemistry; or physical chemistry; Organic chemistry; Physical Sciences; Polymers; Science & Technology; Theoretical and; ALKENES; STANNENE
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om100113c

Germenes Mes2GeCR2 1a (Mes = 2,4,6-trimethylphenyl; CR2 = fluorenylidene) and Mes2GeCR′2 1b (CR′2 = 2,7-di-tert-butylfluorenylidene) react with 1,4-benzoquinone and 2,3,5,6-tetramethyl-1,4-benzoquinone to give compounds 3a, 3b, and 5a, containing a 1,4-cyclohexadiene unit as central ring. Upon prolonged storage in diethyl ether or THF solution, compounds 3a and 3b undergo a double 1,3-hydrogen shift, leading to their structural isomers 4a and 4b. Theoretical calculations performed on the model compound H2GeCH2 1H postulate that the first steps of its reaction with 1,4-benzoquinone are a double [2+2] cycloaddition between the GeC and CO double bonds, leading to a transient dispiro compound containing two oxagermetane rings, followed by its isomerization to derivative 3H. Between 1a and 9,10-anthraquinone, a double [2+4] cycloaddition is observed involving the oxygens and the ortho-carbon atoms of one adjacent aromatic ring system, to generate the dioxadigermabenzopyrene derivative 2a.