Upon reaction with either molecular oxygen or di-tertbutylperoxide in the presence of a simple copper(I) salt and an alcohol, a range of 1,2-azaborines readily exchange B-alkyl or B-aryl moieties for B-alkoxide fragments. This transformation allows alkyl and aryl groups to serve for the first time as removable protecting groups for the boron position of 1,2-azaborines during reactions that are not compatible with the easily modifiable B-alkoxide moiety. This reaction can be applied to synthesize a previously inaccessible BN isostere of ethylbenzene, a compound of interest in biomedical epoxide ring opening using N-deprotonated 1,2-azaborines followed by an intramolecular version of reaction can be applied to access the first examples of BN isosteres of dihydrobenzofurans and compounds that are important to medicinal chemistry and natural product synthesis.