Conjugate nucleophilic additions

In agreement with these analyses, it was found that conqiound S was unreactive toward base-catalyzed cyclization to 6, even though the double bond would be expected to be reactive toward nucleophilic conjugate addition. On the other hand the acetylene 7 is readily cyclized to 8 ... 

Stereoselection of Nucleophilic Conjugate Addition 6.1 Bicyclic Systems... 

Tronchet, J.M.J., Neeser, J.-R., Gonzalez, L., and Charollais, E.J., Preparation of unsaturated sugars phosphonates using nucleophilic conjugate addition, Helv. Chim. Acta, 62, 2022, 1979. 

The thing above the arrow is a fancy version of LDA. C4 and C8 are electrophilic, C9 is unreactive, and Cl is acidic, so first step must be to deprotonate C7 to make it nucleophilic. Conjugate addition to C8 generates a nucleophile at C9, which adds to C4 to give a new enolate. Workup then provides the product. 

The effect of a remote substituent on the facial selectivities in a nucleophilic conjugate addition has been investigated for the reaction of EtSH with a series of dibenzobicyclo[2.2.2]octatrienes (84). Syn-addition proved to be favoured for nitro substituent and polar solvents increased the selectivity (Table 5).19... 

In one of the earliest reports on enantioselective radical reactions, chiral Lewis acid mediated conjugate addition followed by enantioselective H-atom transfer a to a carbonyl was reported by Sato and co-workers (Scheme 3) [22], The single point binding chiral aluminum complex presumably coordinates to the carbonyl oxygen of the lactone as shown in 10. The strong Lewis acidity of the aluminum complex activates the substrate 7 to nucleophilic conjugate addition, which is followed by an enantioselective H-atom transfer from BuaSnH in a chiral environment provided by BINOL ligand in 8. Only 28% ee was observed for product 9. 

The formation of the bicyclic intermediate, VII/157, (Scheme VII/31) was achieved by nucleophilic conjugate addition of tributyltinlithium to cyclohexe-none, reaction of the intermediate ketone enolate ion with a small excess of ethyl vinyl ketone and, subsequently, with a large excess of formaldehyde. The mechanism is analogous to that presented in Scheme VII/9 of Chapter VII. 1. 

Both simple and fused poly substituted pyran-2-ones can be obtained from the reaction between substituted allenyl esters and ketones activated by an electron-withdrawing group. A base-catalysed nucleophilic conjugate addition affords a homoallylic ester and lactonisation completes the one-pot sequence (Scheme 19) <06S2731>. 

Michael additions. The reagent undergoes nucleophilic conjugate addition reactions with R(Ar)OH, R(Ar)SH, RjNH, for example (Sehweizer and Bach ) ... 

Cinchona-Catalyzed Nucleophilic Conjugate Addition to Electron-Deficient C=C Double Bonds... 

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