Abstract Pyrolysis of pyridine (2-benzylphenyl) borane and pyridine (2-benzhydrylphenyl) borane yielded the 9, 10-dihydro-9-boraanthracene system. The ring-closed products were isolated as the ethanolamine esters. An analogouś conversion of pyridine-2- biphenylylborane gave pyridine-9-borafluorene.
