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A Theoretical and X-Ray Study of the Reaction of Vinylene Carbonate with Furan and Cyclopentadiene

Ab initio (RHF/3-21G and 6-31G* basis sets) quantum chemical calculations have been applied to a study of the known Diels-Alder reactions of dichlorovinylene carbonate 1 and vinylene carbonate 8 as dienophiles with cyclopentadiene, furan and fulvene as cyclic 1,3-dienes. The required levels of ab initio theory for reproducing experimental data have been established and key points concerning stereospecificities are addressed. RHF/3-21G and RHF/6-31G* basis sets were used, and energies also estimated by MP2/6-31G* single point calculations. Transition states for these reactions are located and activation energies estimated. The stereochemical outcomes are readily predicted using RHF/3-21G or higher ab initio levels and compared with newly obtained X-ray structures of 4 and 7. Secondary orbital interactions are postulated to contribute to the observed stereospecificities.

furan; cyclopentadiene; cycloadditions; calculations; transition states; X-ray

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