sec.-butyllithium; copper dichloride in tetrahydrofuran; pentane argon atmosphere; addn. of sec-BuLi in pentane to soln. of phosphine-borane in THF (-78.dergee.C), stirring (2 h), addn. of CuCl2 (stirring), warming to room temp., standing (room temp., 1 h); quenching (aq. HCl), extn. (CHCl3), drying of extracts (MgSO4), concn. (vac.), praparatine TLC (silica gel); elem. anal.;