Diversity through Isosterism: The Case of Boron-Substituted 1,2-Dihydro-1,2-azaborines

The first general synthesis of boron-substituted 1,2-dihydro-1,2-azaborines is described. The versatile 1,2-dihydro-1,2-azaborine precursor 4 is
synthesized through a ring-closing metathesis−oxidation sequence. Treatment of 4 with a wide range of anionic nucleophiles furnishes the
desired adducts 5 in good yields. The scope includes hydrogen- and a variety of carbon- and heteroatom-based nucleophiles. Furthermore,
the boron-containing isostere (7) of the potent hypolipidemic agent, methyl 2-ethylphenoxyacetate (8), is readily prepared through our method.