Dialkyl ketones, asymmetric transfer

The development of the first highly enantioselective cyanocarbonation of prochiral ketones promoted by a chiral base catalyst, such as a cinchona alkaloid derivative, was reported by Tian and Deng in 2006. " Importantly, the reaction complemented known enzyme- and transition metal based methods in substrate scope via its unique ability to promote highly enantioselective cyanocarbonation of sterically hindered simple dialkyl ketones. Mechanistic studies provided experimental evidence to shed significant light on the asymmetric induction step in which the modified cinchona alkaloid acted as a chiral nucleophilic catalyst. Moreover, experimental evidence supported the mechanistic proposal that the enantioselectivity determination step in the cyanocarbonation was a DKR of the putative intermediates G and H via asymmetric transfer of the alkoxycarbonyl group (Scheme 2.105). 

V,7V-Dialkyl derivatives of 1 have been successfully applied to the asymmetric addition of dialkylzinc reagents to aldehydes, giving products of moderate enantiomeric excess.In addition, ruthenium(II) complexes of 1 have been demonstrated to be excellent catalysts for the control of the enantioselective transfer hydrogenation of ketones to alcohols at catalyst loadings as low as 1 mol The ruthenium/1 complex has been applied to a range of ketone substrates, including cyclic enones and a-amino and alkoxy substituted derivatives. 

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