- A simple and green procedure for the conjugate addition of thiols to conjugated alkenes employing polyethylene glycol (PEG) as an efficient recyclable medium
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Polyethylene glycol (PEG) is found to be an inexpensive, nontoxic, environmentally friendly reaction medium for the conjugate addition of thiols to conjugated alkenes to afford the corresponding adducts in excellent yields under mild and neutral condition
- Kamal, Ahmed,Reddy, D. Rajasekhar,Rajendar
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- Study of the Michael addition of β-cyclodextrin-thiol complexes to conjugated alkenes in water
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An environmentally benign and highly efficient supramolecular Michael addition of thiols from the secondary side of β-cyclodextrin to α,β-unsaturated compounds at the primary side in water is described in quantitative yields; products of undesirable side
- Krishnaveni, N. Srilakshmi,Surendra,Rao, K. Rama
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p. 669 - 671
(2007/10/03)
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- Pyrolysis of Sulfoxide Bearing Electron-Withdrawing Substituents on β-Position in S-Ethyl Group of Ethyl Phenyl Sulfoxide
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In order to obtain information concerning the reaction mechanism of the pyrolysis of a sulfoxide bearing an electron-withdrawing substituent on the β-position in the S-ethyl group of ethyl phenyl sulfoxide, 2-(substituted phenyl)ethyl aryl sulfoxides (1) and 2-cyanoethyl (substituted phenyl)sulfoxides (2) were pyrolyzed.The rate-enhancing effect of the β-phenyl group of 1 was small.The activation enthalpy and entropy of 1 were found to be 110 kJ mol-1 and -45 JK-1mol-1, respectively.Hammett plots for 1 gave positive trends for the substituents, both on the β-phenyl group (ρ=0.76) and on the S-phenyl group (ρ=0.32), though the ρ-value of the latter was about half of the former.On the other hand, the Hammett plot for 2 did not give a straight line, but a concave curve in which a series of substituents from the p-OCH3 to p-Cl groups gave a negative trend (ρ=-0.49), while the p-NO2 group afforded a positive trend.The pyrolytic rate of 2 was found to be about 23-times faster than that of 1 at 100 deg C.The kinetic isotope effect for β-position hydrogen in the β-phenylethyl group of 1 was considerably large (kH/kD=4.3).From the obtained results, it was suggested that the pyrolysis of 1 and 2 proceeds via a nearly carbanion-like mechanism in a five-membered cyclic transition state.
- Yoshimura, Toshiaki,Yoshizawa, Masaki,Tsukurimichi, Eiichi
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p. 2491 - 2496
(2007/10/02)
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