in dimethyl sulfoxide Irradiation (UV/VIS); mixt. of substrate and mercurial is irradiated in nitrogen-purged solvent in Pyrex tube with 350-nm Rayonet photoreactor for 24 h; mixt. is poured into water, extd., extract is washed twice with aq. sodium thiosulfate, dried over anhyd. Na2SO4, concd.; (1)H-NMR;