| Summary: | 碩士 === 靜宜大學 === 應用化學系 === 101 === A series of 1-aryl-2,2-dichlorocyclopropanes were prepared by reaction of styrenes and chloroform the presence of potassium tert-butoxide to form 1-aryl-2- chlorocyclopropenes. The cycloprorene ring concaining carbons with sp2 hybrid character tend to transform into with the carbons with sp3 hybrid character to release the ring strain energy. This characteristic of 1-aryl-2-chlorocyclopropenes lead it to react with cyclopentadiene via a Diels-Alder [4+2] cycloaddition. A series of 2-chloro-4-aryl-exo-tricyclo[3.2.1.02,4]-oct-6-ene and 2-chloro-4-aryl-endo-tricyclo[3.2.1.02,4]-oct-6-ene.
Based on the 1H NMR spectral analysis, the endo form is supposed as only product. However, the small amount of 2-chloro-4-aryl-exo-tricyclo[3.2.1.02,4]-oct-6-ene also can be detected form the GC/MS analysis. Unusual long range 5J coupling was observed in the COSY spectra due to the W conformation in the rigid structure of endo isomers in the liquid state.
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