Conjugate Addition to a, 3-Unsaturated Carbonyl Compounds

Ammonia and amines undergo conjugate addition to a 3 unsaturated carbonyl compounds (Section 18 12) On the basis of this information predict the pnncipal organic product of each of the following reactions... 

The formed vinylic cuprates readily perform conjugate addition to a,)3-unsaturated carbonyl compounds giving 8-vinyl-substituted ketones. 

Stabilized anions exhibit a pronounced tendency to undergo conjugate addition to a, 3-unsaturated carbonyl compounds. This reaction, called the Michael reaction, has been described for anions derived from (3-diketones in Section 18.13. The enolates of ethyl acetoacetate and diethyl malonate also undergo Michael addition to the (3-carbon atom of a,(3-unsaturated aldehydes, ketones, and esters. For example,... 

Throughout this review, elimination reactions have b n restricted to Ae loss of an appropriate leaving group from the a-carbon atom, but both 3-thio and -selenenyl groups can be eliminate with ease from C >X compounds following oxidation.As a rule, such derivatives are prepared by conjugate addition to a, 3-unsaturated carbonyl compounds, and therefore formation and elimination constitutes a formal protection of these compounds. 

The RuH2(PPh3)4-catalyzed addition of active methylene compounds can also be applied to conjugate additions to a,/3-unsaturated carbonyl compounds (Michael additions). In 1989, Murahashi reported the first example of the transition metal-catalyzed Michael addition of active methylene compounds [74]. One of the notable advances of this catalytic reaction is that the addition of C-H bonds to a,/3-unsaturat-ed carbonyl compounds give Michael adducts without contamination by the corresponding aldol products (Eq. 9.56) [74]. Recently, Murahashi applied their aldol and Michael addition reactions to a solid-phase synthesis using polymer-supported nitriles (Scheme 9.12) [76]. In this case, four component reactions took place with high diastereoselectivity. 

Enolates from Conjugate Additions to a,(3-Unsaturated Carbonyl Compounds... 

Other than listed above, the asymmetric conjugate addition to a,(3-unsaturated carbonyl compounds has been also conducted by using organoaluminum species. In 1999, Jacobsen et al. described the highly enantioselective conjugate addition of hydrazoic acid (HN3) to a,(3-unsaturated imides catalyzed chiral salen-organoaluminum complex 59 (Scheme 42) [75]. 

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