Palladium-catalyzed cross-coupling of aryl chlorides with O, N-chelate stabilized diarylborinates

A series of O, N-chelated diarylborinates have been prepared and tested as arylboron counterpart alternative to oxygen-labile diarylborinic acids in palladium catalyzed Suzuki coupling of aryl chlorides. 3-Dimethylaminopropyl diarylborinates (B-5a), featuring a six-membered O, N-chelated boron ring that was confirmed by single crystal X-ray diffraction, displayed a delicately balanced stability and reactivity. Their cross-coupling with structurally various aryl chlorides could be effected as efficiently as that of the parent diarylborinic acids by using 0.1∼1mol% Pd(OAc)2/IPr/P(OPh)3 as catalyst system, to provide the corresponding biaryls in good to excellent yields.