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

The cycloaddition reaction of tert-butylcyanoketene (TBCK, Mooreʹs ketene) with 1,3-cyclopentadiene yields the [2+2] product, namely cyclobutanone 9. TBCK and 1,3-cyclohexadiene provide the cyclobutanone 10 and some of the ether 11. Both reactions yielding the cyclobutanones (9 and 10, respectively) are reversible. Cyclobutanone 10 is converted thermally and irreversibly into the bicyclic ether 11 via a [3,3] sigmatropic rearrangement (oxo-Cope). The X-ray single crystal data for the ether 11 confirms that the CN and the ether oxygen are in a trans configuration. Data provided by density functional calculations at B3LYP/6-311++G(d,p) level mirror the X-ray data. Furthermore, the relative thermodynamic stabilities (ΔG calculated at 273 °C, 1 atm) of the most relevant isomers of 10 at mPWB1K/6-31+G(d,p) level of theory is provided. Details of the transition states that: (i) leads to cyclobutanone 10 from TBCK and 1,3-cyclohexadiene, and (ii) the oxo-Cope rearrangement of cyclobutanone 10 to produce ether 11 are provided.