HALLER-BAUER CLEAVAGE OF CYCLOPROPYL PHENYL KETONES

A number of cyclopropyl phenyl ketones substituted on the small ring were subjected to the Haller-Bauer reaction to resolve some inconsistencies in the literature and to learn more of the factors which determine the direction of cleavage. The results may be understood in terms of fragmentation to give the more stable carbanion intermediate except in the cases of (Z)-2-phenylcyclopropyl phenyl ketone and 1-methyl-2,2-diphenylcyclopropyl phenyl ketone. Steric relief appears to play an important role in these two examples. The original report of Haller and Benoist regarding the major products from cleavage of 1-methylcyclopropyl phenyl ketone is believed to be in error. © 1969, American Chemical Society. All rights reserved.