Scope and diastereoselectivity of intramolecular [4+2] Diels–Alder cycloaddition reactions of (η6-arene)Ru(DMPP)Cl2 complexes with dieneophilic ligands

The complexes (η6-arene)Ru(DMPP)Cl2 (DMPP=3,4-dimethyl-1-phenylphosphole; arene=C6H6, MeC6H5, p-MeC6H4CHMe2, and C6Me6) react with NaPF6 and the dieneophilic ligands: Ph2PCHCH2 (DPVP), Me2NC(O)CHCH2 (DMAA), MeC(O)CHCH2 (MVK), PhSCHCH2 (PVS), PhS(O)CHCH2 (PVSO), and 2-vinylpyridine (2VP) to produce [(η6-arene)Ru(syn-exo-2-R-5,6-dimethyl-7-phenyl-7-phosphabicyclo [2.2.1] hept-5-ene)Cl]PF6 complexes (R=PPh2, C(O)NMe2, C(O)Me, PhS, PhS(O), and 2C5H4N, respectively) with high diastereo-selectivities. Similar reactions of (η6-arene)Ru(DMPP)Cl2 with NaPF6 and allyldiphenyl-phosphine (ADPP) produced the mixed ligand complexes [(η6-arene)Ru(DMPP) (ADPP)Cl2]PF6 which did not undergo subsequent [4+2] Diels–Alder cycloadditions even at elevated temperatures. New complexes were characterized by elemental analyses, physical properties, cyclic voltammetry, infrared spectroscopy, 1H-, 1H{31P}-, 13C{1H}-, and 31P{1H}-NMR spectroscopy and in most cases by X-ray crystallography.