ALKYLATION OF ENONES AND KETONES USING SUBSTITUTED ALKYLALUMINUM AND ARYL-ALUMINUM COMPOUNDS

The reactions of RnAlX3-n compounds (where R = Me, Et, and Ph and X = Cl, Br, I, OCH3, t-BuO, 0-2, 2, 6, 6-Me4(cHx) and NiPr2) with enones and cyclohexanones have been studied under varying conditions of solvent, temperature, and stoichiometry. The purpose of the study was to explore the effect of increased steric requirement of the RnA1X3-n compounds on the regioselectivity of addition to enones and the stereoselectivity of addition to cyclohexanones. It has been shown that a direct relationship exists in both cases in that Me2AlI and Ph2AlI addition to enones results in much greater 1, 4-addition (as high as 100%) than that of the corresponding R3A1 or R2A1X compounds (where X = Cl and Br). A direct relationship between the steric requirement of the reagent and stereoselectivity of cyclohexanone addition has also been demonstrated. Both Ph2AlX and Me2AlX compounds have been shown to produce increasing amounts of equatorial alcohol in benzene as the steric requirement of the X group increases. © 1979, American Chemical Society. All rights reserved.