Conjugate trapping reactions

As previously mentioned, allenes can only be obtained by 1,6-addition to acceptor-substituted enynes when the intermediate allenyl enolate reacts regioselectively with an electrophile at C-2 (or at the enolate oxygen atom to give an allenyl ketene acetal see Scheme 4.2). The regioselectivity of the simplest trapping reaction, the protonation, depends on the steric and electronic properties of the substrate, as well as the proton source. Whereas the allenyl enolates obtained from alkynyl enones 22 always provide conjugated dienones 23 by protonation at G-4 (possibly... 

Review Taylor has reviewed the conjugate addition-enolate trapping reactions of organocopper reagents, in particular of lithium dialkylcuprates (131 references). 

R. J. K. Taylor, Organocopper Conjugate Addition-Enolate Trapping Reactions, Synthesis 1985, 364. 

Li K, Alexakis A (2007) Copper-catalyzed enantioselective intramolecular conjugate addi-tion/trapping reactions synthesis of cyclic compounds with multichiral centers. Chem-Eur J 13 3765-3771... 

Metal-Catalyzed Tandem Conjugate Addition/Electrophilic Trapping Reactions... 

In this area, Krische and co-workers have developed a family of catalytic transformations based on the use of enones as latent enolates. Nucleophilic activation of the enone is induced via carbometallation, nucleophilic organocatalysis or hydrometallation. The following examples illustrate some aspects of these new catalytic conjugate addition/electrophilic trapping reactions. 

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