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[摘要]：The boron trichloride mediated reaction of aryl aldehydes and alkynes can be used to selectively generate either (Z,Z)- or (Z,E)-1,5-dichloro-1,4-dienes as major products, depending on the reaction conditions employed. To investigate the mechanism of this important carbon-carbon bond forming reaction, the boron trichloride mediated reaction of phenylacetylene with p-bromobenzaldehyde was chosen as the model system. Interestingly, when the coupling reactions are carried out below 60 degrees C, (E,E)-1,5-dichloro-1,4-dienes are also formed. The ratios of (Z,Z)-, (Z,E)-, and (E,E)-1,5-dichloro-1,4-dienes were correlated to the reaction conditions using gas chromatography-mass spectrometry. The results of the investigation can be used to explain why the ratio of (Z,E)-, (Z,Z)-, and (E,E)-1,5-dichloro-1,4-pentadiene products change very dramatically when changes are made in either the sequence of addition of the reagents or the reaction temperature. |
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