- RuO4-mediated oxidation of N-benzylated tertiary amines. Four- And three-membered azacycloalkanes as substrates
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Similarly to N-benzylpiperidine and -pyrrolidine, N-benzylazetidine underwent RuO4-catalyzed oxidation by attack at both types of N-methylene C-H bonds: Endocyclic and exocyclic (benzylic). If the reaction is performed in the presence of cyanide, α-aminon
- Florea, Cristina A.,H?rtopeanu, Anca,Stavarache, Cristina,Petride, Horia
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p. 294 - 307
(2018/11/26)
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- Electrogenerated Superoxide-Activated Carbon Dioxide. A New Mild and Safe Approach to Organic Carbamates
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The electrochemical reduction of O2 (E = -1.0 V vs SCE) in dipolar aprotic solvents in the presence of CO2 gave a carboxylating reagent (O2·-/CO2) able to convert amines and different types of their derivatives into carbamates. Primary and secondary aliphatic and aromatic amines were converted into the corresponding ethyl carbamates by the addition of EtI to the carbamate anions generated in the first step of the reactions. The yields were dependent on the nucleophilicity of the nitrogen atom ω-Bromoethyl- and propylamine gave 2-oxazolidinone and tetrahydro-l,3-oxazm-2-one in moderate yields. N-Acyl or N-(alkoxycarbonyl)alkylamines bearing a leaving group at the β position of the alkyl substituent were converted into 3-substituted-2-oxazolidinones in high yields. By using chiral substrates, enantiopure 3-alkoxycarbonyl(or acyl)-4-substituted oxazolidin-2-ones (70-85% isolated yields) were obtained. This represents a new mild and safe route to these important auxiliaries for asymmetric synthesis. Some limitations of the process are also evidenced and accounted for.
- Casadei, Maria Antonietta,Moracci, Franco Micheletti,Zappia, Giovanni,Inesi, Achille,Rossi, Leucio
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p. 6754 - 6759
(2007/10/03)
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- Effect of Distortion on the Hydrolytic Reactivity of Amides. 2. N-Pyramidalization: Decomposition of N-Benzoylaziridines in Aqueous Media
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The decomposition of para-substituted N-benzoylaziridines (H, OCH3, NO2, Br) in buffered aqueous media is studied at 25 deg C as a function of pH in order to assess the effect of N-pyramidalization on the hydrolytic reactivity of the amide bond.Overall, the reaction shows three dominant terms: OH- and H2O attack on the neutral form and H2O attack on the protonated form of the amide.In base, the exclusive reaction is rate-limiting and irreversible attack of OH- on the C=O unit leading to normal hydrolytic products.This is shown by the first-order dependence on -> from pH 8 to 14 of the hydrolysis rate and by the fact that ca. 50percent 18O-enriched amide recovered from the hydrolysis medium as a function of time shows no 18O loss.Relative to N,N-dimethylbenzamide (kOH-25 deg C = 6.0 * 10-6 M-1 s-1), N-benzoylaziridine is ca. 200 000-fold more susceptible to OH- attack (kOH-25 deg C = 1.1 M-1 s-1).The kOH- terms follow a ?ρ relationship with ρ = 1.68.In acid, the products are not the expected hydrolytic ones of benzoic acid and aziridine.Rather, exclusive ring opening occurs to give p-X-C6H4C(=O)NHCH2CH2OX.In acetate buffers, product analysis by 1H NMR indicates that the ring-opened material consists of alcohol and acetate (X = H and C(=O)CH3).
- Slebocka-Tilk, H.,Brown, R. S.
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p. 805 - 808
(2007/10/02)
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