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Nucleophilic addition aldehydes/ketones

Figure 19.14 Carboxylic acid derivatives have an electronegative substituent Y = -Br, —Cl, -OR, -NR2 that can be expelled as a leaving group from the tetrahedral intermediate formed by nucleophilic addition. Aldehydes and ketones have no such leaving group and thus do not usually undergo this reaction. Figure 19.14 Carboxylic acid derivatives have an electronegative substituent Y = -Br, —Cl, -OR, -NR2 that can be expelled as a leaving group from the tetrahedral intermediate formed by nucleophilic addition. Aldehydes and ketones have no such leaving group and thus do not usually undergo this reaction.
In addition to nucleophilic additions, aldehydes and ketones show an unusual acidity of hydrogen atoms attached to carbons alpha (adjacent) to the carbonyl group. These hydrogens are referred to as a hydrogens, and the carbon to which they are bonded is an a carbon. In ethanal, there is one a carbon and three a hydrogens, while in acetone there are two a carbons and six a hydrogens. [Pg.127]

The Fewis base-catalysed additions of alkynyl nucleophiles to aldehydes, ketones, and imines have been described.161 Mechanistic studies strongly indicated that the use of new triethoxysilylalkynes facilitate access of a reactive hypervalent silicate intermediate (Scheme 24). [Pg.271]

We have seen at least two examples of nucleophilic addition to ketones and aldehydes. A Grignard reagent (a strong nucleophile resembling a carbanion, R= ) attacks the electrophilic carbonyl carbon atom to give an alkoxide intermediate. Subsequent protonation gives an alcohol. [Pg.839]

The original Mannich reaction is the acid-catalyzed aminomethylation of enohz-able ketones with non-enolizable aldehydes and ammonia, primary amines, or secondary amines, which involves nucleophilic addition of ketone enols to iminium salts generated in situ from the aldehydes and the nitrogen compounds [183]. This three-component coupling reaction provides a powerful tool for carbon-carbon bond formation and introduction of nitrogen functionality. The classical Mannich reaction has some drawbacks in reaction efficiency, regioselectivity, and appli-... [Pg.457]

Tris(methylthio)methyllithium undergoes nucleophilic addition to ketones and aldehydes to give adducts whose hydrolysis affords a-hydroxy esters [Scheme 2,122], whereas conjugate addition of tris(methylthio)methyllithium and tris(phenylthio)methyllithium to butenolides was used in syntheses of Pro-tolichesterenic Acid and Nephrosteranic Acid respectively [Scheme 2.123]. [Pg.106]

The nucleophilic addition reaction is the most common general reaction type for aldehydes and ketones. Many different kinds of products can be prepared by nucleophilic additions. Aldehydes and ketones are reduced by NaBH4 or UAIH4 to yield primary and secondary alcohols, respectively. Addition of Grignard reagents to aldehydes and ketones also gives alcohols (secondary and tertiary, respectively), and addition of HCN delds cyanohydrins. Primary amines add to carbonyl compounds yielding imines, or Schiff bases, and secondary... [Pg.761]

The anions, generated in situ by desilylation of silylacetylenes, allylsilanes, propargylsilanes, a-silyloxetanones, bis(trimethylsilylmethyl) sulfides, and other silane derivatives,can undergo nucleophilic addition to ketones and aldehydes (eq 11). Al-(C,C-bis(trimethylsilyl)methyl) amido derivatives can add to aldehydes followed by Peterson alkenation to form acyl enamines. Treatment of 2-trimethylsilyl-l,3-dithianes can generate dithianyl anions, which are capable of carbocyclization via direct addition to carbonyl or Michael addition (eq 12). The fluoride-catalyzed Michael additions are more general than Lewis acid-catalyzed reactions and proceed well even for those compounds with enolizable protons and/or severe steric hindrance (eq 13). ... [Pg.359]

Aldehydes and Ketones Nucleophilic Addition to the Carbonyl Group... [Pg.703]

ALDEHYDES AND KETONES NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP... [Pg.703]

The next section explores the mechanism of nucleophilic addition to aldehydes and ketones There we 11 discuss their hydration a reaction m which water adds to the C=0 group After we use this reaction to develop some general principles we 11 then survey a number of related reactions of synthetic mechanistic or biological interest... [Pg.712]

PRINCIPLES OF NUCLEOPHILIC ADDITION HYDRATION OF ALDEHYDES AND KETONES... [Pg.712]

Principles of Nucleophilic Addition Hydration of Aldehydes and Ketones... [Pg.713]

Carey Organic Chemistry I 17 Aldehydes and Ketones I Text Fifth Edition Nucleophilic Addition to... [Pg.714]

See other pages where Nucleophilic addition aldehydes/ketones is mentioned: [Pg.736]    [Pg.358]    [Pg.212]    [Pg.78]    [Pg.123]    [Pg.346]    [Pg.736]    [Pg.346]    [Pg.797]    [Pg.817]    [Pg.736]    [Pg.357]    [Pg.346]    [Pg.797]    [Pg.459]    [Pg.418]    [Pg.596]   
See also in sourсe #XX -- [ Pg.57 , Pg.140 , Pg.142 , Pg.143 , Pg.144 , Pg.145 , Pg.146 , Pg.147 , Pg.148 , Pg.149 , Pg.150 , Pg.151 , Pg.152 , Pg.153 , Pg.154 , Pg.160 ]



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ALDEHYDES AND KETONES NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP

Addition aldehydes

Addition ketones

Aldehydes nucleophiles

Aldehydes nucleophilic addition

Conjugate Nucleophilic Addition to a,-Unsaturated Aldehydes and Ketones

Ketones nucleophiles

Ketones nucleophilic addition

Key Concepts—Aldehydes and Ketones—Nucleophilic Addition

Nucleophilic Addition Reactions of Aldehydes and Ketones

Nucleophilic Addition to a, j3-Unsaturated Aldehydes and Ketones

Nucleophilic addition aldehydes and ketones

Nucleophilic addition to a 3 unsaturated aldehydes and ketone

Nucleophilic addition to aldehydes and ketones

Nucleophilic addition to carbonyl groups aldehydes and ketones

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