Structure and Photochemistry of Four Adamantylacetophenones

The photochemistry and crystal structures of four α-adamantylacetophenones have been studied, namely, 1-(4-fluorophenyl)-2-(tricyclo[3.3.1.1^3,7]dec-1-yl)ethanone [(1a), C₁₈H₂₁FO], 1-(4-cyanophenyl)-2-(tricyclo[3.3.1.1^3,7]dec-1-yl)ethanone [(1b), C₁₉H₂₁NO], 1-(4-cyanophenyl)-2-(3-methyltricyclo[3.3.1.1^3,7]dec-1-yl)ethanone [(1c), C₂₀H₂₃NO] and 1-(4-carboxyphenyl)-2-(3-methyltricyclo[3.3.1.1^3,7]dec-1-yl)ethanone [(1d), C₂₀H₂₄O₃]. All four molecules adopt fairly similar conformations, with short γH...O contacts permitting hydrogen abstraction in the photochemical reactions. However, three of the compounds, (1a), (1b) and (1d), are photostable in the solid state and possible reasons for this unreactivity are considered.

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