Cycloadditions asymmetric amplification

Examples of asymmetric amplification in Diels-Alder or hetero-Diels-Alder reactions are listed in Table 6 (see page 281), together with an example of amplification during a 1,3-dipolar cycloaddition. 

It has recently been found that Et2Zn promotes the 1,3-dipolar cycloaddition of nitrile oxides to allyl alcohol in the presence of catalytic amounts of diisopropyl tartrate (DIPT). By this method, 2-isoxazlines are obtained in good yields and up to 96% ee (Eq. 8.73).124a A positive nonlinear effect (amplification of ee of the product) has been observed in this reaction. There is an excellent review on positive and negative nonlinear effects in asymmetric induction.124b... 

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