Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives

Yardimci, Sengul Dilem
Kaya, Nihal
Balcı, Metin
The photooxygenation of the 1-methyl-, 2,3-dimethyl-, and 1,4-dimethylcyclohexa-1,4-dienes, which are readily available through Birch reduction, yielded the corresponding ene-products. The formed endocyclic dienes were trapped by the addition of singlet oxygen to give the corresponding bicyclic endoperoxy hydroperoxides. In the case of 1-methylcyclohexa-1,4-diene and 1,4-dimethylcyclohexa-1,4,-diene, the cis-effect determined the product distribution. Photooxygenation of 2,3-dimethylcyclohexa-1,4-dienes gave mainly exocyclic olefin, which was attributed to the lowered rotational barrier of the methyl group and increased reactivity of the methyl groups.


Highly efficient and selective olefination of acyl phosphonates with ethyl diazoacetate catalyzed by a cobalt(II) porphyrin complex
Erturk, Erkan; Demir, Ayhan Sıtkı (Elsevier BV, 2008-08-04)
The cobalt(II) porphyrin complex (CoTPP) was found to be an efficient catalyst for the Wittig type olefination of acyl phosphonates with ethyl diazoacetate (EDA) in the presence of triphenylphosphine (Ph(3)P). By using this one pot methodology under mild conditions, densely functionalized vinyl phosphonates were obtained in high yields and high E/Z selectivities in relatively short reaction times. A rather broad substrate spectrum and steric influence on the reaction rate were observed.
Regioselective alkylation of dianions of cyclic 1.3-diketones via their monodimethylhydrazones. Synthesis of C-4 substituted cyclic 1.3-diketones
Enders, Dieter; Demir, Ayhan Sıtkı (Elsevier BV, 1989-1)
Cyclic 1.3-diketones are transformed into the corresponding monodimethylhydrazones, which can be alkylated regioselectively at C-4 via dianions with various alkyl halides. The regioselective alkylation of cyclic 1.3-diketones 1, to 4-substituted derivatives 4 is described.
Indium triflate-catalyzed coupling of indoles with acyl phosphonates: synthesis of bis(indolyl)methane phosphonates
Dasbasi, Teslima; Polat-Cakir, Sidika; Abdullah, Meysun; Demir, Ayhan Sıtkı (Elsevier BV, 2011-05-13)
The coupling reaction of N-methylindole with alkyl and aryl phosphonate is described. The reaction works in the presence of 10 mol % of indium triflate and furnished bis(indolyl)methane phosphonates in good yield and high selectivity.
Asymmetric aldol addition of alpha-azido ketones to ethyl pyruvate mediated by a cinchona-based bifunctional urea catalyst
Okumus, Seda; Tanyeli, Cihangir; Demir, Ayhan Sıtkı (Elsevier BV, 2014-07-30)
The first asymmetric synthesis of ethyl 4-aryl-3-azido-2-hydroxy-2-methyl-4-oxobutanoates via a cinchona organocatalyst induced aldol addition of alpha-azido ketones to ethyl pyruvate has been developed. The coupling reaction under optimized conditions was carried out to furnish tetrafunctionalized synthons with enantioselectivities of up to 91:9 and enriched diastereoselectivities of up to 95:5 (syn:anti).
Manganese(III) acetate-mediated oxidative coupling of phenylhydrazines with furan and thiophene: a novel method for hetero biaryl coupling
Demir, Ayhan Sıtkı; Reis, O; Emrullahoglu, M (Elsevier BV, 2002-09-30)
A convenient new method for the arylation of furan and thiophene with arylhydrazine and manganese(III) acetate is described. Oxidation of arylhydrazines with Mn(III) acetate in furan or thiophene affords the corresponding 2-aryl-substituted furans and thiophenes in good yield using commercially available materials; access to 2-substituted heterobiaryls works selectively, and coupling occurs with loss of the hydrazine moiety.
Citation Formats
S. D. Yardimci, N. Kaya, and M. Balcı, “Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives,” TETRAHEDRON, pp. 10633–10638, 2006, Accessed: 00, 2020. [Online]. Available: