Studies in Enantioselective Transition Metal Catalysis Using Modular Phosphine-Phosphite Ligands Copper-catalyzed 1,4-Addition of Grignard Reagents to alpha,beta-Unsaturated Carbonyl Compounds

Beschreibung

The conjugate addition (1,4-addition) of carbon nucleophiles to alpha,beta-unsaturated carbonyl compounds belongs to the most valuable methods of carbon-carbon bond formation in organic synthesis. Of particular synthetic importance is the Cu-catalyzed addition of organometallic reagents to cyclic enones, a process which also represents the benchmarking reaction in the development of new efficient catalyst systems. The Cu-catalyzed conjugate addition of Grignard reagents to different cyclic alpha,beta-unsaturated carbonyl compounds using TADDOL-derived phosphine–phosphite as chiral ligands was investigated. The 1,4-addition products were obtained with enantioselectivities of up to 93% ee. Additionally, the scope of the method was evaluated by testing differently substituted aryl-Grignard reagents. As a most important result it was demonstrate that some of the phosphine–phosphite ligands allow (for the first time) to achieve the Cu-catalyzed 1,4-addition of aryl-Grignard reagents with useful levels of regio- and enantioselectivity (up to 95% ee).
The conjugate addition (1,4-addition) of carbon nucleophiles to alpha,beta-unsaturated carbonyl compounds belongs to the most valuable methods of carbon-carbon bond formation in organic synthesis. Of particular synthetic importance is the Cu-catalyzed addition of organometallic reagents to cyclic enones, a process which also represents the benchmarking reaction in the development of new efficient catalyst systems. The Cu-catalyzed conjugate addition of Grignard reagents to different cyclic alpha,beta-unsaturated carbonyl compounds using TADDOL-derived phosphine–phosphite as chiral ligands was investigated. The 1,4-addition products were obtained with enantioselectivities of up to 93% ee. Additionally, the scope of the method was evaluated by testing differently substituted aryl-Grignard reagents. As a most important result it was demonstrate that some of the phosphine–phosphite ligands allow (for the first time) to achieve the Cu-catalyzed 1,4-addition of aryl-Grignard reagents with useful levels of regio- and enantioselectivity (up to 95% ee).

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Qaseem Naeemi

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