The boron p-orbital has been shown to serve a prominent role in regulating EnT catalysis. As such, we anticipated that moving to a tetrahedral boronate hybridization state may have an adverse effect on excited state energy, resulting in reaction inhibition. However, to our surprise, the use of a BMIDA moiety 36 had little to no effect on reactivity (Scheme 4A), forming the target cyclobutane 37 with enhanced diastereoselectivity in comparison to the analogous boronic ester 1. This probe indicates that excitation efficiency is contingent solely on conjugation of the diene system and is not regulated by the boron p-orbital. Indeed, the reaction was shown to be comprehensively selective with alternative functionalities (Scheme 4B), including electron withdrawing groups (38 and 39) or in the absence of any substituent (40). While further reaction probes of substrate 36 confirmed inefficient homodimerization (Scheme 4b), this also unveiled an unexpected geometric isomerization process that counterintuitively occurred at the alternative alkene site to that of which 2+2 cycloaddition occurs (Scheme 4b). This result was particularly intriguing, given that comprehensive selectivity of the E-isomer product is obtained after 2+2 cycloaddition (Scheme 4a). The observed anomaly inspired us to embark on an in-depth mechanistic analysis to reveal the origin of site selectivity and reaction divergence.