36613-93-1Relevant academic research and scientific papers
Investigation on the regioselectivities of intramolecular oxidation of unactivated C-H bonds by dioxiranes generated in Situ
Wong, Man-Kin,Chung, Nga-Wai,He, Lan,Wang, Xue-Chao,Yan, Zheng,Tang, Yeung-Chiu,Yang, Dan
, p. 6321 - 6328 (2007/10/03)
We found that dioxiranes generated in situ from ketones 1-6 and Oxone underwent intramolecular oxidation of unactivated C-H bonds at δ sites of ketones to yield tetrahydropyrans. From the trans/cis ratio of oxidation products 1a and 2a as well as the retention of the configuration at the δ site of ketone 5, we proposed that the oxidation reaction proceeds through a concerted pathway under a spiro transition state. The intramolecular oxidation of ketone 6 showed the preference for a tertiary δ C-H bond over a secondary one. This intramolecular oxidation method can be extended to the oxidation of the tertiary γ′ C-H bond of ketones 9 and 10. For ketone 11 with two δ C-H bonds and one γ′ C-H bond linked respectively by a sp3 hydrocarbon tether and a sp2 ester tether, the oxidation took place exclusively at the δ C-H bonds. Finally, by introducing proper tethers, regioselective hydroxylation of steroid ketones 12-14 have been achieved at the C-17, C-16, C-3, and C-5 positions.
Thermal Addition of Alkanes to Alkenes, IV. Regioselectivity in the Addition of Cyclohexane to 1,2-Disubstituted Alkenes
Metzger, Juergen O.,Klenke, Kurt,Hartmanns, Joerg,Eisermann, Doris
, p. 508 - 513 (2007/10/02)
Alkanes can be added to alkenes in a free radical chain reaction ("ane reaction").Regioselectivity in the addition of cyclohexane to (E)-3-alkyl substituted methyl acrylates have been measured at 300-450C.The ratio of the two regioisomers 3 and 4 shows a correlation with steric substituent constants Es.Relative rates of the addition of cyclohexyl radical to the alkene and β-scission of the adduct radical versus H-transfer from cyclohexane are determining the ratio of the regioisomers.A minor temperature dependence of regioselectivity has been observed.In relation to the products 3 and 4, ane reaction at a temperature of 450C can be more selective than radical addition reaction at room temperature.Regioselectivity of the addition of cyclohexane to methyl cinnamate at 360-420C shows a slight polar substituent effect.Electron withdrawing substituents have been shown to increase product ratio 4/3.
HOCHDRUCK-HOCHTEMPERATUR-REAKTIONEN IN EINEM STROEMUNGSREAKTOR-VI. THERMISCHE ADDITION VON ALKANEN AN ALKENE
Metzger, Juergen,Hartmanns, Joerg,Koell, Peter
, p. 1891 - 1894 (2007/10/02)
The thermal Anti-Markownikow-addition of alkanes to activated and desactivated alkenes ("direkte substituierende Addition", "Ane-reaction") at 650-723 K and reaction times of 1-10 min. is described.
