And the Robinson annulation

Scheme 5.1-33 The Knoevenagel condensation and the Robinson annulation in [HMIM][PFg],...

The use of a-thiophenyl enones (106 Scheme 12) allows the preparation of phenols such as (107) from cyclic ketones (18).30 The same product can also be obtained by normal Robinson annulation of methyl vinyl ketone (30) and the p-keto sulfoxide (lOS).30 Acceptors other than a, 3-unsaturated carbonyls have been used in both the Michael reaction and the Robinson annulation process. For example, nu-... 

Besides the aldol reaction to form y0-hydroxyketone, 1,3-Dipolar Cycloaddition can also form similar molecules. In addition to the Mukaiyama Aldol Reaction, the following are also similar or closely related to the aldol reaction the Claisen-Schmidt Condensation (the aldol reaction between benzaldehyde and an aliphatic aldehyde or ketone in the presence of relatively strong bases to form an o, )0-unsaturated aldehyde or ketone), the Henry Reaction (base-catalyzed addition of nitroalkane to aldehydes or ketones), the Ivanov Reaction (the addition of enediolates or aryl acetic acid to electrophiles, especially carbonyl compounds), the Knoevenagel Reaction (the condensation of aldehydes or ketones with acidic methylene compounds in the presence of amine or ammonia), the Reformatsky Reaction (the condensation of aldehydes or ketones with organozinc derivatives of of-halo-esters), and the Robinson Annulation Reaction (the condensation of ketone cyclohexanone with methyl vinyl ketone or its equivalent to form bicyclic compounds). 

The more useful synthetic applications based on chemistry in this chapter are formation of allylic halides from conjugated dienes, Michael addition of organocuprates to conjugated compounds, and the Robinson annulation. The homework has synthetic problems that address these transformations. 

The entire manifold of aldol-type condensation reactions. The aldol condensation itself (Equation 9.45, el seq) and all of those in Table 9.5 (viz. the Claisen, Stobbe, Perkin, and Knovenagel condensation reactions and the Robinson annulation). 

The reactions described in this chapter include some of the most useful and frequently employed synthetic methods for carbon-carbon bond formation aldol and Claisen condensation reactions, the Wittig and related olefination reactions, and the Robinson annulation. All of these processes involve, at some point, the addition of a carbon nucleophile to a carbonyl group. The type of product which is isolated depends on the nature of the substituent (X) on the carbon nucleophile, the substituents (A and B) on the carbonyl group, and the ways in which A, B, and X affect the reaction pathways available to the intermediate formed in the addition step. 

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