Structural Aspects of the Nucleophilic Attack of Ketone Enolate on Dehydrodihydropyran

The results of the crystal structure analyses of (6RS,7SR,8RS)-7- methyl-8-phenyl-3-oxabicyclo[4.2.0]oct-1-en-8-ol (C₁₄H₁₆O₂), (1SR,2RS,8RS)-8- methylthio-3-oxatricyclo[6.4.0.0^2,7]dodec-6-en-1-ol (C₁₂H₁₈O₂S) and (1RS,2RS,6SR,7SR,8RS)-8-methyl-3-oxatricyclo[6.4.0.0^2,7]dodeca-1,6,7-triol (C₁₂H₂₀O₄) allow interpretation of the nucleophilic attack reactions of ketone enolates on the short-lived dehydrodihydropyran intermediate, showing that the presence of the O atom influences the reactivity of the dienic system. The structure and conformation of the above compounds are discussed.

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