Unique trans-syn-cis [6.6.7] Tricycle Derivative from Transannular Diels-Alder Contraction of a Model 15-Membered trans-cis-cis Macrocyclic Triene

A model 15-membered trans-cis-cis macrocyclic triene (trans-cis-cis)-tetramethyl (4E,11Z,13E)-5-formylcyclopentadeca-4,11,13-triene-1,1,8,8-tetracarboxylate, C₂₄H₃₂O₉, was synthesized and led to the exclusive formation of a trans-syn-cis [6.6.7] tricyclic compound upon a transannular Diels-Alder reaction. The structure of the precursor and a p-bromobenzoyl analog of the product, (trans-syn-cis)-tetramethyl [rac-(1S,2S,7R,10R)-(8Z)-1-(4-bromobenzoyloxymethyl)tricyclo[8.5.0.0^2,7]pentadec-8-ene-5,5,13,13-tetracarboxylate] ethanol solvate, 3C₃₁H₃₇BrO₁₀.0.76C₂H₆O, were determined in order to establish their exact geometries and ring-junction stereochemistries.

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