1,2-Dihydro-1,2-azaborine is an aromatic chemical compound with properties intermediate between benzene and borazine. Its chemical formula is CBNH. It resembles a benzene ring, except that two adjacent carbons are replaced by nitrogen and boron, respectively. Several other 1,2-azaborines have been synthesized.
After decades of failed attempts, the compound was synthesized in 2008 and reported in January 2009.
One of the synthetic steps is a ring-closing metathesis (RCM) reaction: