Asymmetric synthesis allyl organometallics

The asymmetric synthesis of amino acids via the addition of allyl and 2,3-dimethyl-2-bulenyl organometallics to ( — )-8-phenylmenthyl A-methoxyiminoacetate (14) was examined12. The results show that both allyl- and 2,3-dimethyl-2-butenylzinc bromide provide good stercocontrol. 

The allene synthesis strategy outlined in equation 21 can be rendered asymmetric if non-racemic sulfoxides such as 47a are employed26. The diastereoselective step is an equilibration of the sp3-allylic organometallic species 53 before the -elimination step (equation 23). 

SINGLE ASYMMETRIC SYNTHESIS REACTIONS OF ACHIRAL ALDEHYDES AND CHIRAL ALLYL ORGANOMETALLICS... 

A number of highly enantioselective chiral allyl organometallic reagents have been described in the literature. These are of considerable interest both for the asymmetric synthesis of homoallyl alcohols as well as in double asymmetric reactions with chiral C=X electrophiles. - Two distinct groups of chiral allyl metal reagents can be identified those with conventional, easily introduced chiral auxiliaries and ones in which the center of chirality is a structural component of the reagent (e.g. allyl metal compounds with substituents at C-1). These are discussed separately in the sections that follow. 

We have seen in Section 1.1.3 that reactions of many allyl organometallics and chiral C=X electrophiles proceed with only modest levels of relative diastereoselection. Significant improvement in dia-stereoselectivity is possible, however, by using double asymmetric synthesis, that is, by using the highly enantioselective allyl metal reagents described in Section 1.1.4 rather than the less diastereoface-selec-tive achiral allyl metal compounds discussed in Section 1.1.3. Double asymmetric synthesis is also... 

The addition of allyl and prenyl organometallics (84) to 8-(-)-phenylmenthyl A/-methoxyiminoacetate (83 equation 19) has been examined for the asymmetric synthesis of amino acids. Treatment of (83) with allylboronates and allylzinc bromide affords N-alkoxyamines (85) and (86 Table 19). Both allyl-... 

To be accurate, the definition should be restricted to asymmetric reactions catalyzed by a combination of l,r-binaphthalene-2,2 -diol (BINOL, 4) and Ti(0 -Pr)4. Nonetheless, this chapter will give some background on non-chiral Lewis acid promoters, and include other asymmetric catalytic systems. We will not discuss the allylations that are promoted by Lewis bases, which are reviewed elsewhere, nor cover the reactions with other electrophiles. Excellent reviews already exist on "Selective Reactions Using Allylic MetaM and Catalytic Enantioselective Addition of Allylic Organometallic Reagents to Aldehydes and Ketones , as well as in the comprehensive monograph "Modern Carbonyl Chemistry. The use of BINOL-based catalysts in other fields of organic synthesis has also been reviewed. ... 

Tissot M, Li H, Alexakis A (2014) Copper-catalyzed asymmetric conjugate addition and allylic substitution of organometallic reagents to extended multiple-bond systems. In Alexakis A, Krause N, Woodward S (eds) Copper catalyzed asymmetric synthesis. Wiley-VCH, Weinheim, pp 69-84... 

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