New economical, convenient procedures for the synthesis of catecholborane

Catecholborane was conveniently synthesized by the reaction of tri-O-phenylene bis-borate (2) with diborane in triglyme or tetyaglyme at moderate temperatures (70-80 degreesC). The product, catecholborane, can be distilled out in 85% yield with >97% purity. The tri-O-phenylene bis-borate also reacts with borane-Lewis base complexes, such as BH3:DMS, BH3:THF, and BH3: NR3, with or without solvent, providing catecholborane of high purity in good yields.