Conjugate addition catalyzed

Figure 18. Stereochemical model for conjugate additions catalyzed by arenethiolato—copper complexes. [Adapted from (145, 146).]...

Scheme 3.2 Asymmetric conjugate addition catalyzed by chiral phosphine-rhodium complexes [7-11].

Scheme 3.6 Catalytic cycle for the conjugate addition catalyzed by a rhodium-acetylacetonato complex [16].

I 3 Rhodiumllj-Catalyzed Asymmetric Addition of Organometallic Reagents to Electron-Deficient Olefns Tab.3.2 Asymmetric conjugate addition catalyzed by [Rh(OH)((S)-BINAP)]2 [15],... 

Scheme 3.7 Stereochemical pathway in the conjugate addition catalyzed by the rhodium-(S)-BINAP complex [6, 20, 25].

Maddaford reported the diastereoselective synthesis of C-glycosides 29 using conjugate addition catalyzed by cationic rhodium catalysts such as [Rh(COD)2]BF4 (Eq. 1) [24]. Addition of phosphine hgands to the reaction system inhibited the conjugate addition. It is likely that the enone 28 derived from the pyranose is less reactive toward the conjugate addition. 

Coupling of organometallics. The demetallative dimerization of RLi by CuCl2 is different from the conjugate addition catalyzed by Cul. Organostannanes RSnBuj give R—R when R is an alkynyl, alkenyl, or aryl group."... 

After Takemoto s studies, Bartoli and Melchiorre have successfully used 3-ketoesters and 1,3-diketones in the conjugate addition to iV-benzyl maleimides employing the natural cinchona alkaloids quinine or quinidine as catalysts [267]. The reaction, which is one of the few reported examples of a very stereoselective conjugate addition catalyzed by quinine (or quinidine), affords highly functionalized products with two adjacent stereogenic carbon atoms in high diastereo- (up to 92/2 dr) and enantioselectivity (up to 98% ee) with cyclic and acyclic P-ketoesters... 

Hosseini-Sarvari, M. and Tavakolian, M. 2012a. P-C bond formation via direct and three-component conjugate addition catalyzed by ZnO nano-rods for the synthesis of 2-oxindolin-3-yl-phosphonates under solvent-free conditions. New J. Chem. 36 1014-1021. 

Scheme 2.40 Enantioselective conjugate addition catalyzed by bimetallic complex 135 and consecutive aldol addition of aluminum enolate 136.

The C9 thiourea derivative 23 [67] was appUed in a plethora of organic reactions. Much of this research has been reviewed elsewhere (see, for example. References [3e,g,i,j]) and demonstrates the outstanding potential and versatility of thiourea-derived cinchona alkaloids for organocatalysis. Recently, several studies were concerned with conjugate additions catalyzed by C9 thiourea derivatives. For example. 

FIGURE 23.11 Conjugate additions catalyzed by Lewis acids. 

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