Manganese-Mediated Intermolecular Arylation of H-Phosphinates and Related Compounds

The intermolecular radical functionalization of arenes with aryl and alkyl H-phosphinate esters, as well as diphenylphosphine oxide and H-phosphonate diesters, is described. The novel catalytic Mn-II/excess Mn-IV system is a convenient and inexpensive solution to directly convert C-sp2-H into C-P bonds. The reaction can be employed to functionalize P-stereogenic H-phosphinates since it is stereospecific. With monosubstituted aromatics, the selectivity for para-substitution increases in the order (RO)(2)P(O)H<(RP)-P-1(O)(OR)H<Ph2P(O)H, a trend that may be explained by steric effects.