Reaction of Moore's ketene (tert-butylcyanoketene) with 1,3-cyclopentadiene and 1,3-cyclohexadiene. Is periselectivity controlled by the dynamic of trajectories at the bifurcation point?

TBCK reacts reversibly with 1,3-cyclopentadiene to yield cyclobutanone 9 only. At low temperature (−20 °C) TBCK and 1,3-cyclohexadiene afford cyclobutanone 10 (ca. 75%) and the ether 11 (ca. 25%). The preparation of ether 11 is increased by the oxo-Cope thermal rearrangement of cyclobutanone 10. Ether 11 structure is supported by X-ray diffraction results. Only two transition states have been identified computationally (mPWB95/6-31+G(d,p)), one leading to cyclobutanone 10 and the other to oxo-Cope rearrangement to form ether 11.