Ring Opening Metathesis Polymerization (ROMP) of the Dewar Isomer of 1,2-Azaborinine, a B-N Isostere of Benzene

The first example of the polymerization of a Dewar isomer of an azaborinine heterocycle is reported. Con-trolled ring-opening metathesis polymerization was accomplished with Grubbs and Hoveya-Grubbs 2nd genera-tion catalysts (G2, HG2), as well as a Z-selective Ru catalyst (HGM2001). The unprecedented structure of the polymers containing 4-membered B-N heterocycles was verified by GPC, multinuclear and 2D NMR. Differ-ences in regiochemistry of polymers derived from G2/HG2 versus the Z-selective catalyst HGM2001 were sub-stantiated by 2D NOESY, FT-IR and Raman analyses. The incorporation of B-N heterocycles into these polymer structures is promising as a novel route to functional polymers that contain polar side groups.