Amines, 3-hydroxy kinetic resolution

This mechanism is the same as that of 19-23 the products differ only because tertiary amine oxides cannot be further oxidized. The mechanism with other peroxyacids is probably the same. Racemic (3-hydroxy tertiary amines have been resolved by oxidizing them with t-BuOOH and a chiral catalyst one enantiomer reacts faster than the other.This kinetic resolution gives products with enantiomeric excesses of > 90%. 

The enzymatically catalyzed kinetic resolution of amino alcohols has been established on the multi-ton scale by BASF [7] (Scheme 7.14). Initial studies gave poor selectivity for the unprotected alcohols, as the resolution of trows-2-aminocyclopen-tanol (racemic 28) gave the amine (S,S) 29 and the amide (R,R) 30 in 25% . When the hydroxy functionality was protected as an ether, then resolution of racemic benzyl ether 31 proceeds with high to the give the amine (S,S) 32 and the RR amide 33 with >99.5 and 93 % respectively [33, 34]. 

The [3-hydroxy amines are a class of compounds falling within the generic definition of Eq. 6A.6. When the alcohol is secondary, the possibility for kinetic resolution exists if the Ti-tartrate complex is capable of catalyzing the enantioselective oxidation of the amine to an amine oxide (or other oxidation product). The use of the standard asymmetric epoxidation complex (i.e., T2(tartrate)2) to achieve such an enantioselective oxidation was unsuccessful. However, modification of the complex so that the stoichiometry lies between Ti2 (tartrate) j and Ti2(tartrate)1 5 leads to very successful kinetic resolutions of [3-hydroxyamines. A representative example is shown in Eq. 6A.11 [141b,c]. The oxidation and kinetic resolution of more than 20 secondary [3-hydroxyamines [141,145a] provides an indication of the scope of the reaction and of some... 

Resolution of -hydroxy t-amines. These amines can undergo kinetic resolution by partial oxidation of one enantiomer to the N-o[Pg.92]

In a related reaction using a different Ti(OlV)4/DIPT catalyst it was found that kinetic resolution of racemic /6-hydroxy amines could be effected by enantioselective A-oxide formation. The A-oxide could be reduced to the chiral (S) j6-hydroxyamine using LiAlH4 in THF or by catalytic hydrogenation. In addition 2,3-epoxyalcohols... 

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