The [4.3.0]heterobicyclic title structure, C(19)H(14)BNO(3), is composed of a five-membered OBNC(2) ring and a six-membered OBNC(3) ring, each of which has an approximate envelope conformation. The coordination geometry of the B atom is distorted tetra-hedral. In the crystal structure, centrosymmetrically related mol-ecules are associated through pairs of O-H⋯O hydrogen bonds.