Aldehyde and Ketone Reactions

A few years ago, Blagonev and Ivanov described the bis-deprotonation of aryl acetic acids by Grignard reagents. These magnesinm dianions, known as Ivanov reagents, react with aldehydes and ketones. Reaction between dianions of phenylacetic acid and benzaldehyde yields the anti S-hydroxy acid as the major diastereomer anti/syn 69/22) (equation 113). This result is in agreement with the formation of a cyclic chair-like transition state according to the model of Zimmerman-Traxler . 

Both the hydroxy aldehydes or aldehyde alcohols and the hydroxy ketones or ketone alcohols undergo the characteristic aldehyde and ketone reactions due to the carbonyl group. They react with hydrogen cyanide, phenyl hydrazine and hydroxyl amine. These reactions have been discussed in connection with the aldehydes (pp. 116, 224) and will be considered again when we study the carbohydrates. The carbohydrates in fact belong here with these hydroxy aldehyde and hydroxy ketone compounds but on account of other relations they are better considered at a later time. 

Aldehyde and Ketone Reactions.—(i) The formation of addition prodmts with hydrogen cyanide, H—CN. (2) The formation of oxime compounds with hydroxyl amine, H2—NOH. (3) The formation of hydrazone compounds with a benzene compound known as phenyl hydrazine, H2N—NH—CeHs. 

Oximes and Hydrazones.—The characteristic aldehyde and ketone reactions with hydroxyl amine and phenyl hydrazine, depending upon the carbonyl group, = C = O, take place with the aromatic aldehydes and ketones just as they do with the aliphatic and yield oximes and hydrazoneSy the former being of especial importance. 

Similar information is available for other bases. Lithium phenoxide (LiOPh) is a tetramer in THF. Lithium 3,5-dimethylphenoxide is a tetramer in ether, but addition of HMPA leads to dissociation to a monomer. Enolate anions are nucleophiles in reactions with alkyl halides (reaction 10-68), with aldehydes and ketones (reactions 16-34, 16-36) and with acid derivatives (reaction 16-85). Enolate anions are also bases, reacting with water, alcohols and other protic solvents, and even the carbonyl precursor to the enolate anion. Enolate anions exist as aggregates, and the effect of solvent on aggregation and reactivity of lithium enolate anions has been studied. The influence of alkyl substitution on the energetics of enolate anions has been studied. ... 

Primary and secondary amines add to a,j8-unsaturated aldehydes and ketones to yield jS-amino aldehydes and ketones. Reaction occurs rapidly under mild conditions, and yields are good. Note that the conjugate addition product is often obtained to the complete exclusion of the direct addition product. 

Several procedures are available for the preparation of the requisite p-hydroxysi-lanes such as addition of a-silyl carbanions to aldehydes and ketones, reaction of organocuprates with a,P-epoxysilanes, reduction of P-ketosilanes, and addition of organometallic regents to P-ketosilanes. The selection of a particular procedure is dictated by the structure and stereochemistry of the desired alkene. 

Compounds derived from Aldehydes and Ketones Reaction between PCI3 and Unsaturated Ketones, Mechanism of Reaction of PClj with Benzaldehyde, 1 4 Addition of Phenyldichlorophosphme, Interaction of Phosphorus Halides with Distyryl Ketone and Phenyl Cinnamylidene Methyl Ketone, Action of PCI3 on turated Aldehydes and Ketones, Interaction of Di-phenylohlorophosphine with Benzaldehyde and Benzal etophenone, Addition of Alkoxy- and Aryloxy-chlorophosphines to Carbonyl Compounds— Phosphorus Derivatives of Dimethylaniline— Derivatives of Dibenzyl-methane and Hydroxymethylene Camphor— Heterocydio Rings containing... 

We see that the addition of hydrogen to an aldehyde produces a primary alcohol, whereas the addition to a ketone gives a secondary alcohol. Notice that these reactions are reductions that are essentially the reverse of the alcohol oxidations used to prepare aldehydes and ketones (Reactions 4.1 and 4.2). 

AdditioD ReactioDS to Aldehydes and Ketones Reactions at the Carbonyl Carbon (C-0)... 

Preparation of aldehydes and ketones Reactions of aldehydes and ketones—General considerations Nucleophilic addition of H and —A review Nucleophilic addition of "CN... 

A more neaily typical rtaiction of the sugar group is that with phemlliydrazme. resulting in the formation of an osazone. The tir T >tep iv exaetly ana]ogou with the usual aldehyde and ketone reactions. continuetl heating with phenylhvdrazine solu-... 

Cinchona-based primary amine catalysis in the asymmetric functionalization of carbonyl compounds has been reviewed and their modularly designed thioamide 0 derivatives have been applied successfully to direct cross-aldol reactions between aldehydes and ketones, reactions of activated carbonyl compounds (isatins) with acetylphosphonate as the enol precursor, and C( 1) functionalization of 1,3-dicarbonyl compounds by aldehydes and ketones. Cross-aldol addition to C(3) of isatins by the methyl group of 4-aryl-tra 5 -cf, -unsaturated methyl ketones has also been promoted... 

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