Alkylation of allylic derivatives. 11. Copper(I)-catalyzed cross coupling of allylic carboxylates with Grignard reagents

Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium‐Catalyzed Allylic Alkylation

“…Despite the success of those allylation methods,t he use of nonstabilized nucleophiles in palladium-catalyzed allylation is still extremely limited. [8] Later, Hoveyda, [9] Feringa, [10] and others made systematic investigations on the use of organomagnesium reagents for allylic substitutions. Thei ntroduction of the Grignard reagents as cross-coupling partners with allylic substrates represented am ajor step forward, enabling facile access to adiverse range of alkenes as shown by the groups of Swierczewski [7] and Goering.…”

The Copper-Catalyzed Asymmetric Allylic Substitution

“…The control of the regioselectivity depends on the nontransferable group R T . A halide or cyanide group usually allows high γ selectivity, whereas an alkyl group (as in R 2 CuLi) allows an equilibration, thus favoring the substitution at the least sterically hindered carbon [8][9][10][11][12][13][14].…”

An insight into copper catalyzed allylation of alkyl zinc halides. Comparison of reactivity profiles for catalytic and stoichiometric alkylzinc–copper reagents

“…If we assume that the allylation of alkylzinc-copper reagents may take place according to the mainly accepted mechanism (Scheme 2, M + = ZnCl + ) proposed by Goering and co-workers [52][53][54][55] and Backvall et al [21] for allylation of alkylmagnesium-copper reagents, then we should find support for the following points: 1. In the Cu catalyzed c-allylation of alkylzinc reagents, reductive elimination seems to occur predominantly from r-allyl-Cu(III) complex B rather than r-allyl-Cu(III) complex D. Then, X group on the zinc cuprate seems to be mainly halide, CN or SCN rather than alkyl, or in other words RCu(X)ZnCl rather than R 2 CuZnCl seems to form as catalytic species.…”

“…According to the mechanism proposed by Goering and co-workers [52][53][54][55] and confirmed by Backvall et al [21] (Scheme 2), initial complexation of RCu(X)MgBr to the allylic double bond gives an alkene-Cu(I) complex A and an oxidative addition anti to the leaving group takes place at vinylic terminal. The r-allyl-Cu(III) complex intermediate B thus formed can undergo reductive elimination to give c-product or isomerize to the r-allyl-Cu(III) complex intermediate D formed at allylic terminal, presumably via a p-allyl-Cu(III) complex intermediate C. Reductive elimination of D would give the a-product.…”