cis-anti-cis-Tricyclo[6.4.0.0^2,7]dodecane-3,12-dione and cis-anti-cis-Tricyclo[6.4.0.0^2,7]dodecane-3,9-dione

The single-crystal X-ray structures of two photochemical products of 2-cyclohexenone have identified them as the head-to-head and head-to-tail cis-anti-cis dimers (C₁₂H₁₆O₂) formed by 2 + 2 addition. The cyclobutane ring is twisted in the head-to-head isomer but flat in the head-to-tail compound.

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