And conjugate addition

This IS called direct addition ox 1 2 addition (The 1 and 2 do not refer to lUPAC locants but are used m a manner analogous to that employed m Section 10 10 to distin guish between direct and conjugate addition to conjugated dienes)... 

Chiral Cu(ll)-complexes ofbis-oxazolines as Lewis acids for catalyzed cycloaddition, carbonyl addition, and conjugate addition reactions 99PAC1407. 

Gothelf presents in Chapter 6 a comprehensive review of metal-catalyzed 1,3-di-polar cycloaddition reactions, with the focus on the properties of different chiral Lewis-acid complexes. The general properties of a chiral aqua complex are presented in the next chapter by Kanamasa, who focuses on 1,3-dipolar cycloaddition reactions of nitrones, nitronates, and diazo compounds. The use of this complex as a highly efficient catalyst for carbo-Diels-Alder reactions and conjugate additions is also described. 

Since aromatic substitutions, aliphatic substitutions, additions and conjugate additions to carbonyl compounds, cycloadditions, and ring expansion reactions catalyzed by Fe salts have recently been summarized [17], this section will focus on reactions in which iron salts produce a critical activation on unsaturated functional groups provided by the Lewis-acid character of these salts. 

CO 1 0 c 1 X r Nucleophilic substitution and conjugate addition to unsaturated ketones ketones from acyl chlorides b,c... 

CH3)3CO—Cu—R] Li Nucleophilic substitution and conjugate addition to ra,p-unsatu rated ketones b... 

Evans, D.A., Hurst, K.M., and Takacs, J.M., New silicon-phosphorus reagents in organic synthesis. Carbonyl and conjugate addition reactions of silicon phosphite esters and related systems, /. Am. Chem. Soc., 100, 3467, 1978. 

In this chapter, only additions to unactivated systems are reported and conjugate addition considerations, crosscoupling reactions, and cross-metathesis are covered in Chapters 10.08, 11.01, 11.02, 11.08, 11.09, and 11.10. 

Scheme 10 Vitamin Bi2-mediated cyclization and conjugate addition to prostaglandin PGF2o .

Figure 10.3 shows snapshots of intermediary species on the potential surface of carbocupration to illustrate the transformation of the reacting complex. The formation of the transient carbolithiated intermediate INT2 is the most striking feature, because recognition of this intermediate provides the key to understanding of the kinship of carbocupration, Sn2 allylation (Sect. 10.4.2), and conjugate addition. 

Although acetylene carbocupration and conjugate addition have previously been considered to be two separate reactions, they have been shown to share essentially the same reaction mechanism. The kinship of carbocupration, conjugate addition, Sn2 allylation, and Sn2 alkylation has now been established, through the theoretical studies of Nakamura, Mori, and Morokuma. 

Simple 1,2-addition is often favoured with good nucleophiles, and conjugate addition with weaker... 

Scheme 26 Aldol and conjugate addition reactions require different types of stabilization for the transition state...

The proposed catalytic cycles for the iminium ion catalysed Diels-Alder cycloaddition and conjugate addition reactions are outlined in Fig. 2. The general principles of these catalytic cycles can be used to understand each of the reactions described within this review which all follow a similar mechanistic pathway. The catalytic cycle consists of three principle steps ... 

Fig. 2 Catalytic cycles for the iminium ion activated Diels-Alder and conjugate addition reactions...

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