boron trifluoride diethyl etherate; ammonium chloride in dichloromethane Ar; -78°C; slow addn. of BF3*Et2O; after 1 h hydrolysed with NH4Cl/H2O at room temp.;; aq. layer extd. with Et2O; combined organic layers dried over Na2SO4; evapd.; chromd. (Al2O3, CH2Cl2).; identified by spectroscopy;;

boron trifluoride diethyl etherate; ammonium chloride in dichloromethane Ar; -78°C; slow addn. of BF3*Et2O; after 1 h hydrolysed with NH4Cl/H2O at room temp.; yields: 71percent;; aq. layer extd. with Et2O; combined organic layers dried over Na2SO4; evapd.; chromd. (Al2O3, CH2Cl2).; identified by spectroscopy;;