In an effort to gain further insight into this HAT event and the formation of the linear product 8, we conducted a deuterium labeling study using isotopically enriched α-CD 3 styrene 2'a-CD 3 with phenyl gem-diborylalkene 1a under our optimized conditions (Figure ). The desired products 3af and 8g were obtained with deuterium incorporation at the benzylic position of product 8g, thereby confirming the formation of product 8g through a possible 1,5-HAT pathway as discussed in Figure This radical I-3-D 3 underwent a 1,5-hydrogen (deuterium) atom transfer (HAT). Finally, this a hydrogen (deuterium) atom transferred to the benzyl position (See I-3-D 3 and 8g). This facilitates the coupling of the two remaining radicals, generating a double bond and yielding the desired product 8g (Figure ). Nevertheless, the formation of this linear product 8 might alternatively support the EnT operation to the diborylated alkene 1. Encouraged by the results observed in the decarbonation-type reaction of the double bond in gem-diborylalkene 1, we anticipated the possibility of applying the EnT [2+2]-cycloaddition protocol to couple polyborylated alkenes-namely, tri-and tetra-borylated alkenes 4 and 6, respectively-with olefins 2 (Figure ). This envisioned decarbonation-type pathway holds the potential not only to produce a more complex and highly borylated class of cyclobutanes e.g. 5 and 7, a category that is still underdeveloped, but also to generate a fundamentally new class of polymetalated-biradical species II-III (Figure ).