Palladium-catalysed cross-coupling reaction of ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole compounds with aryl bromides: A direct protocol for the preparation of unsymmetrical biaryls.

There has been a significant interest in organoboron compounds such as arylboronic acids, arylboronate esters and potassium aryltrifluoroborate salts because they are versatile coupling partners in metal-catalysed cross-coupling reactions. On the other hand, their nitrogen analogues, namely, 1,3,2-benzodiazaborole-type compounds have been studied extensively for their intriguing absorption and fluorescence characteristics. Here we describe the first palladium-catalysed Suzuki-Miyaura cross-coupling reaction of easily accessible and ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole derivatives with various aryl bromides. Aryl bromides bearing electron-withdrawing, electron-neutral and electron-donating substituents are reacted under the catalytic system furnishing unsymmetrical biaryl products in isolated yields of up to 96% in only 10 minutes.

2-(3-Meth-oxy-phen-yl)-1,3-dihydro-1,3,2-benzodiaza-borole.

The title compound, C(13)H(13)BN(2)O, is one in a series of 1,3,2-benzodiaza-boroles featuring a 2-meth-oxy-phenyl substitution at the 2-position in the nitro-gen-boron heterocyle. The dihedral angle between the mean planes of the benzodiaza-borole and 2-meth-oxy-phenyl ring systems is 21.5 (1)°. There is an inter-molecular hydrogen bond between one of the NH groups and the meth-oxy O atom. This hydrogen bond leads to an infinite hydrogen-bonded chain colinear with the a axis.