The invention relates to processes for the synthesis of aryl or alkene borates which comprises reacting: (i) an olefinic compound having a halogen or halogen-like substituent in a vinylic substitution position, or (ii) an aromatic ring having a halogen or halogen-like substituent in a ring substitution position, with a disubstituted monohydroborane in the presence of a Group 8 11 metal catalyst. The invention also relates to the use of these borates in coupling reactions. The invention further relates to certain disubstituted monohydroboranes and aryl or alkene borates.