Kharasch and Sosnovsky reported the allylic oxidation of alkenes to give racemic allylic benzoates. This could be achieved efficiently using a tert‐butyl perester as the oxidant, in the presence of a copper or cobalt salt. The use of C2‐symmetric bis(oxazoline) ligands in the presence of copper(I) triflate with cyclic olefinic substrates gave the first synthetically useful asymmetric variant. The enantioselective control was good (up to 84 % ee) although yields were variable. In all cases the facial preference of the newly formed C−O bond was the same giving an S configuration at the allylic stereocenter. Lower stereocontrol was observed for large‐ring alkenes and substantially reduced enantioselectivities were found with open‐chain alkenes. This reaction has been further screened using a variety bis(oxazoline) and proline‐derived ligands, which give a direct correlation between the chirality of the ligand and the enantioselectivity obtained. Individual substrates were found to be extremely sensitive to both the ligand structure and copper salt used as well as the presence of additives such as zinc, hydrazine, and molecular sieves.

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An Efficient Protocol for Sharpless-Style Racemic Dihydroxylation.-Racemic dihydroxylation of various alkenes is efficiently achieved under conditions similar to those of Sharpless asymmetric dihydroxylation using OsCl 3 -quinuclidine as catalytic system and methanesulfonamide as a further additive. Scope and limitation of the reaction are studied, and diastereoselectivity in the dihydroxylation of compounds with stereogenic centers, e.g. (VII) and (IX), is found to be only moderate.