Catalyst-free regio- and chemoselective addition of secondary phosphine oxides to isoquinolines

Isoquinolines react with secondary phosphine oxides without catalyst (70–75 °C, 10–15 h, without solvent or in MeCN) to chemo- and regioselectively form previously unknown diadducts, 1,3-bis(diorganylphosphoryl)-1,2,3,4-tetrahydroisoquinolines, in high yields (85–95%).