Divergent oxidative rearrangements in solution and in a zeolite: distal vs proximal bond cleavage of methylenecyclopropanes.
Irradiation of 9,10-dicyanoanthracene (DCA) or p-chloranil in the presence of E-1-benzylidene-2-phenylcyclopropane (E-5) in CH(2)Cl(2) causes E-5 to undergo methylenecyclopropane rearrangement. An adduct, Z-7, between DCA and 5 firmly supports the involvement of a bifunctional trimethylenemethane radical cation. In contrast, incorporation of E-5 into HZSM-5 produces trans,trans-1,4-diphenyl-1,3-butadiene radical cation sequestered in the HZSM-5 interior, tt-8(.+)@HZSM-5, identified by ESR and diffuse reflectance spectroscopy. In addition, low yields of tt-8, its cis,trans-isomer (ct-8), and 1-phenyl-1,2-dihydronaphthalene (9) were isolated from the supernatant solution. The sharp contrast between the photoinduced electron-transfer reaction with photosensitizers in solution and the spontaneous reaction with redox-active acidic zeolite offers the prospect of further zeolite-induced regiodivergent reactions in a range of additional substrates.
Ikeda
Hiroshi
H
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan. ikeda@org.chem.tohoku.ac.jp
Nomura
Tsuyoshi
T
Akiyama
Kimio
K
Oshima
Mitsuhiro
M
Roth
Heinz D
HD
Tero-Kubota
Shozo
S
Miyashi
Tsutomu
T
D018360:Crystallography, X-Ray; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry / Q000528:radiation effects; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010777:Photochemistry; D012996:Solutions / Q000737:chemistry; D013997:Time Factors; D017641:Zeolites / Q000737:chemistry*
D003521:Cyclopropanes; D012996:Solutions; D017641:Zeolites