The reaction between 2-lithio derivatives of aromatic azaheterocycles and trichlorocetyl derivatives rapidly produces the corresponding 2-chloro derivatives in high yields through a metal halogen exchange mechanism. The use of ethyl trichloroacetate can give better results with respect to those obtained with trichloroacetyl chloride, which probably involves dichloroketene formation. The reaction with Grignard reagents is more complex: in fact, 2- ...
