Kharash-Sosnovsky reaction

Oxidations. A widely used method for allylic oxidation is the Kharash-Sosnovsky reaction using a peroxide and a copper(I) salt system. Enantioselective allylic oxidations of cycloalkenes such as cyclopentene, cyclohexene and cycloheptene with tert-butyl peibenzoate were investigated with a variety of catalysts derived from bis(oxazoline) ligands and copper(I) triflate complexes (eq 18). The ligand-copper(I) complexes from the /-Bu-... 

Keywords C-H oxidation, Benzylic hydroxylation, AUylic oxidation, Desymmetrization of meso compound, Kharash-Sosnovsky reaction. Iron-porphyrin complex, (Salen)manganese(lll) complex... 

Several methods are now available for allylic oxidation. Among them, the ene-type oxidation reaction with, e.g., Se02 or 02 oxidation have been the most widely used for the purpose [15] but their asymmetrization has not met with success. Another widely used method is the Kharash-Sosnovsky reaction using a peroxide and Cu(I) salt system [16]. This reaction has been considered to proceed through a Cu(III)-allyl complex 7 (Scheme 6) [17]. 

This mechanism suggests that the reaction can be performed in an enantiose-lective manner, if the copper ion is appropriately modified by chiral ligand(s). In 1965, the Cu(II)-a-ethyl camphorate complex was found to promote the asymmetric Kharash-Sosnovsky reaction, although the enantioselectivity was only modest [18]. Thirty years later, this chemistry was followed by three highly enan-... 

Scheme 12. Other examples of the Asymmetric Kharash-Sosnovsky reaction...

Copper nitrenoids that participate in C—H bond insertion reactions have also been studied for a long time. In 1997, the first asymmetric reaction was reported by Katsuki and co-workers. Their design was derived from the Kharash-Sosnovsky reaction (Scheme 1.52, top), the Cu-catalyzed allylic... 

For a brief discussion on the asymmetric Kharash-Sosnovsky reactions, see Chapter 5, Section 5.5. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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