Herein we report that trans-haloboration of o-alkynyl phenols leads to C4-halogenated benzoxaborinines using BX3 or BX3/[BX4] -combinations. Furthermore, this process tolerates a range of functional groups including an ester at C8 -crucial for accessing BLIs. Finally, the vinyl chloride is an addressable handle: Negishi coupling reactions lead to C-C bond formation without break-up of the boracycle. Thus o-alkynyl-phenol trans-haloboration represents a simple method to access halogenated benzoxaborinines that are useful intermediates for accessing an increasingly important class of bioactives.