Carbonyl Condensations with Amine Derivatives

As might be expected, the carbonyl function in aldoses and ketoses undergoes condensation reactions with amine derivatives (Section 17-9). For example, treatment of o-mannose with phenylhydrazine gives the corresponding hydrazone, o-mannose phenylhydrazone. Surprisingly, the reaction does not stop at this stage but can be induced to continue with additional phenylhydrazine (two extra equivalents). The final product is a double phenylhydrazone, also called an osazone (here, phenylosazone). In addition, one equivalent each of benze-namine (aniline), ammonia, and water is generated. 

Amines can react with various carbonyl compounds and their derivatives in aqueous media to give the corresponding imine derivatives. These reactions have been discussed in related chapters. The synthetically most useful reaction of this type is the formation of imines and imine derivatives from the condensation of amines with aldehydes and ketones. Water is an excellent solvent for such condensation reactions. For example, water was found to be an ideal solvent for a high-yield, fast preparation of easily hydrolyzable 2-pyrrolecarbaldimines.23 In the presence of Cu2+, the reaction afforded the corresponding Cu(II) chelates (Eq. 11.19). 

Schiff base org chem RR C=NR" Any of a class of derivatives of the condensation of aldehydes or ketones with primary amines colorless crystals, weakly basic hydrolyzed by water and strong acids to form carbonyl compounds and amines used as chemical intermediates and perfume bases, in dyes and rubber accelerators, and in liquid crystals for electronics, shif, bas ... 

Organic hydrazines or diazanes are substitution products of NH2—NH2 and have many properties similar to those of amines in being basic and forming acyl derivatives as well as undergoing alkylation and condensations with carbonyl compounds (Section 16-4C). Unsymmetrical hydrazines can be prepared by careful reduction of /V-nitrosamines. l,l-Dimethyldiazane is prepared in this way for use as a rocket fuel ... 

In summary, the SMS reaction is a truly efficient process, possessing a broad scope and applicable to a number of carbonyls, allylsilanes, alcohols (silyl ethers) or amines. Its usefulness has been validated in several total syntheses and demonstrated by the preparation of chiral homoallylic alcohols. During the development of the SMS reaction, Melkafia and Marko [48] realized that the homoallylic alcohol (ether), if connected to an allylsilane, would form novel annelating agents that would lead to tetrahydropyran derivatives via condensation with carbonyl compounds. This reaction was called IMSC for intramolecular Sakurai cydization and will be discussed in the next section. 

Jones, F. N. Vaulx, R. L. Hauser, C. R. o-Meta-lation of benzyldimethylamine and related amines with BuLi. Condensations with carbonyl compounds to form ortho derivatives. 

Aldehydes can arise by Reactions C, D, and E, and they can then react with each other by the aldol condensation. Amines (and particularly their salts), including peptones and egg albumin, are effective catalysts. Additional carbonyl compounds which can participate in the condensation may be derived by the oxidation of lipids. 

Enamines are important functionalities in general organic chemistry their structures being defined by a double bond with a vinyl amine. These structures are easily formed by the addition of amines to carbonyl compounds [70,71]. As shown in Scheme 6.41, the formation of enamines, when applied to sugars, can produce unsaturation at the 2,3 position [72]. In the example shown, a 2-deoxysugar derivative was condensed with pyrrolidine giving the illustrated enamine. 

Chichibabin pyridine synthesis. Condensation of carbonyl compounds with ammonia or amines under pressure to form pyridine derivatives the reaction is reversible and produces different pyridine derivatives and by-products. 

Schiff base. An imine, derived by chemical condensation of aldehydes or ketones with primary amines very weakly basic and hydrolyzed by water to form carbonyl compounds and amines. 

Condensing certain hydrazine derivatives with carbonyl derivatives may, further, lead to heterocycles containing the structural unit of N,iV-acetals (aminals) for instance, 1,2,3,4-tetrahydrophthalazine (13) and formaldehyde give 5,7,9,14,16,18-hexahydrodiphthalazino[2,3-a 2, 3 -d]-,s-tetrazine (14) 970... 

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