The easiest transformation of 3x is to react at the B-OH position, and this is indeed straight forward. For example, the addition of ethanolamine to 3a resulted in quaternization at boron to form compound 10 in effectively quantitative conversion (92% isolated yield, Scheme 3). While a simple conversion this is nevertheless important, as being able to alter substituents and coordination number at boron affords compounds with distinct stability profiles something that is vital during subsequent transformations. For example, the formation of Xeruborbactam from A requires quaternization at boron by addition of an amino alcohol prior to cyclopropanation of the alkene moiety. A transformation that would demonstrate the usefulness of the haloboration process to form benzoxaborinines would be using the vinyl-Cl moiety in a cross coupling reaction. While a number of Suzuki-Miyaura coupling conditions were unsuccessful, viable Negishi cross coupling conditions were identified. Significantly, a one pot haloboration -Negishi coupling protocol was developed that did not require isolation of benzoxaborinines 3x. Instead the primary crude product from the haloboration of o-alkynyl-phenol with BCl3 was taken forward into a Negishi cross-coupling with just a solvent switch required. Using 2-ethynyl-4-phenoxyphenol, 1g, a sequence of haloboration, solvent switch, cross coupling with ZnEt2 and work-up led to the formation of the sp 2 C-Csp 3 coupled product 11, in an overall 53% yield based on the starting alkyne. An identical procedure using ZnPh2 in place of ZnEt2 led to formation of 12 post-work up in 39% yield based on the starting alkyne. In this case the B-chloro-benzoxaborinine has undergone sp 2 C-Csp 2 coupling and arylation at boron. Analysis of intermediates reveal that B-C bond formation also is occurring using ZnEt2, but in this case the B-Et bond is transformed during the work-up to the B-OH, while the B-Ph proved more resistant to B-C cleavage during work-up. However, conversion of the B-Aryl unit to the B-OH can be achieved in a separate step using previously reported conditions to form B-OH containing cyclic boronates from B-Aryl derivatives (Fig. ). Scheme 4: Negishi cross-coupling using crude benzoxaborinine and commercial diorganozinc reagents.