in diethyl ether; hexane; pentane Ar atm.; molar ratio (Ph2PO)2NH:BuLi 1:1, stirring (-50°C), heating (2 h, room temp.), stirring (2 h), cooling (-20°C), stirring (1 h, room temp.); evapn. (vac.), drying (vac.), extraction (n-pentane), filtn., concn., crystn. (-50°C);