Allyl additions double asymmetric induction

Chiral allylic silanes and chiral aldehydes. This combination of agents provides fascinating opportunities for double asymmetric induction and allows the magnitude of the various controlling features to be expressed. The sense and level of 1,2-asymmetric induction in the Lewis acid-promoted addition of chiral E-2-butenylsilanes to chiral a-alkoxy aldehydes has been examined as well (Scheme 10-18) [37j. 

In order to explain the chemistry of allylic metals, the reactions of allylic boron compounds [8,12-14] are covered in detail. The boron chemistry is divided into four parts simple enantioselectivity (addition of CH2=CHCH2-, creating one new stereocenter), simple diastereoselectivity of crotyl additions (relative configuration after CH3CH=CHCH2- addition, where neither reagent is chiral), single asymmetric induction with chiral allyl boron compounds (one and two new stereocenters), and double asymmetric induction (both reactants chiral, one and two new stereocenters). Then follows a brief discussion of other allyl metal systems. 

Table 5.2. Double asymmetric induction in addition of allyl boron compounds to aldehydes. Ligands are illustrated in Figure 5.1.

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