The acid-catalyzed rearrangement of 1-phenylcycloalkyl hydroperoxides has been investigated using the cyclohexyl, cyclopentyl, and cyclobutyl compounds. Evidence was sought for rearrangement of the cycloalkyl group in competition with migration of thephenyl group during the reaction. Such a rearrangement would result in ring expansion of the cycloalkyl group to give, ultimately, products formed by cycloalkyl ring opening.No evidence for such a reaction was found in the case of 1-phenylcyclohexyl hydroperoxide; only the expected products, phenol and cyclohexanone, were detected. However, rearrangement of l-phenylcyclopentyl hydroperoxide gave, besides the expected phenol and cyclopentanone, significant amounts of the ring-opened compound 4-hydroxyvalerophenone as its acetate. A second product, 1-phenylcyclopentene, arose by elimination of hydrogen peroxide from the hydroperoxide.1-Phenylcyclobutyl hydroperoxide proved to undergo ring expansion with great facility. Only the ring expanded products, 2-phenyl-2-tetrahydrofuryl hydroperoxide and its corresponding peroxide, could be isolated in the treatment of 1-phenylcyclobutanol with hydrogen peroxide using catalytic amounts of mineral acids. However, in the absence of catalysts, 1-phenylcyclobutyl hydroperoxide was formed in detectable amounts and its presence was demonstrated by decomposition with ferrous sulfate to butyrophenone and 1,6-dibenzoylhexane.It seems reasonable that ring strain is the factor promoting the ring expansion of 1-phenylcyclobutyl hydroperoxide. In the case of 1-phenylcyclopentyl hydroperoxide, it is suggested that the steric interaction of the ortho hydrogens of the phenyl group with the cyclopentyl ring protons has the effect of slowing the migration of the phenyl group sufficiently that alkyl migration can occur to give the observed ringopened products.

Substituted benzhydryl hydroperoxides have been synthesized and rearranged using sulfuric acid as the catalyst and acetone as the solvent. The products have been analyzed in order to determine the migration aptitudes for the various aryl groups. A linear relationship exists between the log of the migration aptitude and the o+ values of the substituents. Ortho substituents deviate from this relationship but the extent of deviation is much smaller than expected. The migration aptitude of hydrogen versus phenyl in the rearrangement of benzhydryl hydroperoxide has been found to vary markedly depending on the solvent. These observations and their bearing upon the mechanism of the rearrangement are discussed.

1997 stereochemistry stereochemistry (general, optical resolution) O 0030 -053Asymmetric Propargylation/Allylation/Pauson-Khand Cyclization of a Planar Chiral Anisole Tricarbonylchromium Complex.-A new approach is described that involves both the nucleophile addition/allylation step and the Pauson-Khand reaction occurring with complete diastereoselectivity. The sequence demonstrates the efficient transfer of the planar chirality in (I) to the three stereogenic centers in the tricyclic diketone (VI). -(QUAT-TROPANI, A.; ANDERSON, G.; BERNARDINELLI, G.; KUENDIG, E. P.; J.