A norbornenyl derivative with through-space ketone pi-interaction

Area of Science:

• Organic Chemistry
• Crystallography
• Physical Chemistry

Background:

• The title compound, endo,exo-12-oxotetracyclo[6.2.1.1(3,6).0(2, 7)]dodeca-9-en-anti-11-yl p-bromobenzoate (C(19)H(17)BrO(3)), features a complex polycyclic structure.
• It incorporates a norbornene moiety and a norbornanone unit, bridged and substituted in a specific stereochemical arrangement.

Purpose of the Study:

• To characterize the structure and properties of the novel title compound.
• To investigate the spatial relationship and electronic interactions between the ketone and alkene functionalities within the molecule.
• To correlate structural features with observed chemical reactivity, specifically solvolysis rates.

Main Methods:

• X-ray crystallography was employed to determine the precise three-dimensional structure of the compound.
• Spectroscopic methods were likely used for characterization (though not explicitly stated).
• Analysis of the spatial proximity and geometry of the ketone and alkene groups.

Main Results:

• The crystal structure reveals a norbornene core with an anti-p-bromobenzoate substituent and an exo-fused norbornanone unit.
• The ketone and alkene groups are in close spatial proximity, suggesting potential through-space electronic interactions.
• The ketone's carbon atom exhibits significant pyramidalization, indicating deviation from planarity.

Conclusions:

• Through-space pi-interaction between the proximate ketone and alkene groups is proposed as the dominant factor.
• This interaction is likely responsible for the experimentally observed low solvolysis rate of the related anti-11-chloride derivative.
• The study highlights the importance of non-bonded interactions in dictating the reactivity of complex organic molecules.