Selective C-C bond activation of 2-aryl-1-methylenecyclopropanes promoted by Ir(I) and Rh(I) hydrido complexes. Mechanism of ring-opening isomerization of the strained molecules

Yasushi Nishihara, Chikako Yoda, Masumi Itazaki, Kohtaro Osakada

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19 Citations (Scopus)

Abstract

[IrH(CO)(PPh3)3] promotes ring opening of 2-phenyl-1-methylenecyclopropane at room temperature to produce the Ir complex with a chelating 2-phenyl-3-butenyl ligand, [Ir{η2-CH 2CH(Ph)CH=CH2-κC1}(CO)(PPh 3)2] (1). The reaction of excess 2-phenyl-1- methylenecyclopropane with [IrH(CO)(PPh3)3] at 50 °C yields [Ir{η2-(o-C6H4)CH(Me)CH= CH 2-κC1}(CO)(PPh3)2] (2), accompanied by the formation of 1-phenyl-1,3-butadiene and 2-phenyl-1,3- butadiene. 2,2-Diphenyl-1-methylenecyclopropane reacts with [IrH(CO)(PPh 3)3] to afford [Ir{η2-CH 2CPh2CH=CH2-κC1}(CO)-(PPh 3)2] (3) at 50 °C and [Ir{η2-(o-C 6H4)CMe(Ph)CH=CH2-κC1}(CO) (PPh3)2] (4) at 100 °C. Heating a solution of 3 at 100 °C also forms 4 quantitatively. X-ray crystallography of 3 reveals a penta-coordinated structure around the Ir center bonded to a chelating 2,2-diphenyl-3-butenyl ligand. The reactions of 2,2-diphenyl-1- methylenecyclopropane and of 2,2-di(4-fluorophenyl)-1-methylenecyclopropane with [RhH(CO)(PPh3)3] at room temperature yield [Rh{η2-CH2CAr2CH=CH2- κC1}(CO)(PPh3)2] (5a: Ar = Ph, 5b: Ar = C6H4-F-4). The reactions at 50 °C cause ring opening of the substrate and orthometalation of the phenyl group to afford [Rh{η2-(o-C6H4)CMe(Ph)CH=CH 2-κC1}-(CO)(PPh3)2] (6a) and [Rh{η2-(o-C6H3-F-4)CMe(C6H 4-F-4)CH=CH2-κC1}(CO)(PPh 3)2] (6b), respectively. Formation of 1,1-diaryl-1,3- butadiene is observed during the reaction. Heating a solution of Sa at 50 °C produces 1,1-diphenyl-1,3-butadiene and an allylrhodium complex, 8, rather than 6a, although the reaction of excess 2,2-diphenyl-1-methylene-cyclopropane with 5a at 50 °C affords 6a in 60%. The mechanisms of the above reactions are discussed based on the products and reaction rates. Coordination of P(OMe) 3 to the Rh center of 5a causes insertion of the CO ligand into the Rh-C bond to afford [Rh{η2-CO-CH2CPh 2CH=CH2-κC1}(P(OMe)3) 3] (7).

Original languageEnglish
Pages (from-to)1469-1480
Number of pages12
JournalBulletin of the Chemical Society of Japan
Volume78
Issue number8
DOIs
Publication statusPublished - Aug 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

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