Orthoplatination of Primary Amines

The first efficient and general cycloplatination reaction of primary amines is introduced. A precursor obtained from K2PtCl4 and HI undergoes fast substitution by amine ligands; the resulting trans diamine derivative is converted via C−H activation into a cycloplatinated square-planar complex. The reaction proceeds surprisingly fast, under mild conditions and with high yields, even for electron-deficient substrates. The monohapto amine ligand in the product complex may be substituted by alternative donor ligands such as phosphanes or pyridine derivatives. Single-crystal X-ray diffraction studies of a trans compound which is suggested as intermediate, of three target complexes involving electronically different primary amines and of four substitution products are reported and underline the broad range of products accessible by this synthesis.