Applications of organolithium and related reagents in synthesis. Part 3. A general study of the reaction of lithium alkyls with pyridine ketones

Abstract

The reaction of MeLi and PhLi with acetylpyridines (1a–c) and their annelated derivatives (2a), (2b), (3), and (4) has been examined. The 3- and 4-pyridyl ketones (1b), (1c), (3), and (4) gave similar results to acetophenone and 3,4-dihydronaphthalen-1(2H)-one. In the case of the 2-pyridyl ketones (1a), (2a), and (2b) unexpectedly low yields of products resulted from the addition of RLi to the carbonyl group; the reaction was efficiently enhanced by initially adding an additional amount of LiBr. These results were accounted for by the chelation of RLi or LiBr by the 2-pyridyl ketones.