Is Halogen-Lithium Exchange Intramolecularly Competitive with Removal of an Acidic Hydrogen? Reinvestigation of a Recent Claim

Article abstract of DOI:10.1021/ja00021a026

A careful reinvestigation of a recent report in which the iodine-lithium exchanges of 2-iodo-3-(deuterioxymethyl)quinoline (1) and 2-iodo-3-(hydroxymethyl)quinoline (4) are interpreted to have occurred prior to abstraction of the alcoholic hydrogen has been carried out. Accurate analyses of the reaction products by FI mass spectrometry give results that are different from those recently reported and are consistent with a mechanism in which removal of the acidic hydrogen takes place prior to iodine-lithium exchange on a molecular scale. The interpretation that suggested the opposite sequence was based on deuterium incorporation values that appear to be inaccurate due to the limitations of the ¹H NMR methods used.