Structural assignment of a bis-cyclopentenyl-β-cyanohydrin formed via alkene metathesis from either a triene or a tetraene precursor

The identity of the major product of Ru‐catalysed alkene metathesis of two polyene substrates has been determined using density functional theory (DFT) NMR prediction, a 1H–1H Total Correlated Spectroscopy (TOCSY) NMR experiment and ultimately by single‐crystal X‐ray crystallography. The substrates were designed as those that would potentially allow expedient access to the trans‐decalin skeleton of the natural product (−)‐euonyminol, but the product was found to be a bis‐cyclopentenyl‐β‐cyanohydrin [1‐(1‐hydroxycyclopent‐3‐en‐1‐yl)cyclopent‐3‐ene‐1‐carbonitrile, C11H13NO] rather than the trans‐2,3,6,7‐dehydrodecalin‐β‐cyanohydrin.