Negishi Cross-Coupling Is Compatible with a Reactive B–Cl Bond: Development of a Versatile Late-Stage Functionalization of 1,2-Azaborines and Its Application to the Synthesis of New BN Isosteres of Naphthalene and Indenyl

The compatibility of the Negishi
cross-coupling reaction with the
versatile B–Cl functionality has been demonstrated in the context
of late-stage functionalization of 1,2-azaborines. Alkyl-, aryl-,
and alkenylzinc reagents have been utilized for the functionalization
of the triply orthogonal precursor 3-bromo-1-(tert-butyldimethylsilyl)-2-chloro-1,2-dihydro-1,2-azaborine (2) to furnish new 2,3-substituted monocyclic 1,2-azaborines. This
methodology has enabled the synthesis of previously elusive BN-naphthalene
and BN-indenyl structures from a common intermediate.