boron trifluoride diethyl etherate 1.) THF, -30 deg C, 1 h, 2.) carbonyl unmasking; further Lewis acids, temperatures and times; Yield given. Multistep reaction;

boron trifluoride diethyl etherate 1.) THF, -30 deg C, 1 h, 2.) carbonyl unmasking; further Lewis acids, temperatures and times; Yield given. Multistep reaction;