The past twenty years has witnessed the growing utilization of boron as a function providing element in pharmaceuticals. While this development was catalyzed by the approval of Bortezomib, an aminoalkyl boronic acid, the majority of subsequently approved boron containing drugs are B-O boracycle derivatives. One of the most important applications of boracyclic drugs exploits their ability to inhibit -lactamases. Administering a cyclic-boronate  lactamase inhibitor (BLI) alongside a lactam is a leading approach to tackle antibiotic resistance. While Vaborbactam (Fig. ) was the pioneer boronate approved as a BLI, recent work has led to the development of bicyclic boronate BLIs that have the broadest spectrum activity of any BLI reported to date. Notably, the three that are currently in advanced phase clinical trials all have the same core structure (Fig. , red). (Bi)cyclic boronates are not only emerging as BLIs, they also have been applied recently for treating cancer and auto-immune disorders. While their importance is rapidly growing, synthetic approaches to make cyclic boronates remain limited, particularly to form all sp 2 B,O boracyclic systems e.g. oxaborinines. Most reports making cyclic boronate based drugs rely on established yet inefficient approaches (e.g. lithiation-borylation / homologation), or transition metal catalyzed C-X borylation. Therefore the development of alternative routes to form bicyclic boronate structures relevant to bioactives would facilitate exploration in this important area, particularly if the method to form the bicyclic boronate concomitantly incorporated an additional modifiable functional group. Recently, a novel approach to form the BLI with the broadest spectrum of activity, Xeruborbactam, on large scale was reported. This method proceeds via the benzoxaborinine A (Fig. , top) which was accessed by a nickel catalyzed boron insertion into benzofuran B. While notable this approach to benzoxaborinines has functional group limitations (associated with using reactive low valent Ni complexes) and it does not tolerate any substituents at the C3 position of the benzofuran. Therefore developing a new route to benzoxaborinines related to A that has: (i) complementary functional group tolerance; (ii) tolerates esters at C8 (due to the importance of these in BLIs), and (iii) contains a functionalizable handle at the C4 position (the position that would be derived from the C3 of benzofurans on boron insertion) is highly desirable. The haloboration of appropriately functionalized aryl-alkynes would be an attractive route to form C4-halogenated analogues of A. Haloboration forms the required vinyl-B concomitantly with a vinyl halide, the latter being highly amenable to further functionalisations. However, a number of challenges need to be overcome to achieve haloboration, most notably an appropriate group on oxygen is required to preclude alternative reactivity. For example, o-alkynyl anisoles react with BCl3 by oxoboration and not haloboration (Fig. , middle). This is attributed to the Ar(Me)O→BCl3 interaction being weak and BCl3 dissociation leading to activation of the alkyne and thus oxoboration. In contrast, the NMe2 analogue forms a stronger interaction with BCl3 (than O-Me) and reacts via alkyne transhaloboration (to give a five membered boracycle, C, Fig. right). We hypothesized that moving from o-alkynyl anisoles to o-alkynyl phenols will preclude the formation of benzofurans as BX3 will react rapidly with the phenolic OH to irreversibly form an ArylOBX2 and HX. This step lowers the nucleophilicity of the oxygen center (disfavoring alkyne oxoboration with free BX3), while incorporating the boron Lewis acid appropriately for intramolecular activation of the alkyne and thus haloboration. Finally, the formation of an all sp 2 boracycle (as in A) will favor six membered boracycle formation over five membered, making formation of D feasible via this route.