- Organocatalysis as a safe practical method for the stereospecific dibromination of unsaturated compounds
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Organocatalytic stereospecific dibromination of a wide variety of functionalized alkenes was achieved using a stable, inexpensive halogen source, 1,3-dibromo 5,5-dimethylhydantoin, and a simple thiourea catalyst at room temperature. The presence of a tertiary amine enhanced the rate of the dibromination reaction, and yields were good in various solvents, including aqueous solvents. The procedure was extended to alkynes and aromatic rings and to dichlorination reactions by using the 1,3-dichloro hydantoin derivative.
- Hernandez-Torres, Gloria,Tan, Bin,Barbas, Carlos F.
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supporting information; experimental part
p. 1858 - 1861
(2012/06/18)
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- Transmission of substituent effects through extended systems-III. p-Substituted ethyl trans cinnamates and phenylpropiolates
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Infrared data and 13C chemical shifts are reported for a series of ethyl p-substituted trans-cinnamates and ethyl phenylpropiolates.The i.r. values include intensities for the benzene, ethylene and carbonyl vibrations which allow an estimation of resonance effects.The relative importance of the various mechanisms of transmission of substituent effects are discussed and compared to those previously reported for p-substituted trans cinnamonitriles.It is shown that the carbon-carbon triple bond is less efficient in transmitting substituent effects than carbon-carbon double bonds.
- Butt, G.,Topsom, R. D.
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p. 649 - 654
(2007/10/02)
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