hydrogenchloride in dichloromethane standartized soln. of hydrogen chloride in CH2Cl2 (ca. 5 molar equiv) was added dropwise at -78°C, mixt. was stirred for 6-8 h, soln. was allowed to warm to room temp.; solvent was evapd., residue recrystd. from CH2Cl2/hexane (1/3); elem. anal.;