1: hexadeuterioacetone 2: acetone View Scheme

in dichloromethane dropwise addn. of HBF4 in CH2Cl2 to soln. of the 1-metalla-1,3-diene in CH2Cl2 (under inert gas, 20°C, under vigorous stirring); not isolated; 1H-NMR, 13C-NMR, IR;