Amines derivatives, carbonyl condensations

Fig. 10 Synthesis of imidazolines or benzimidazoles by condensation of an additional amine with the carboxylic acid-derived carbonyl...

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. 

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. 

Reaction of disecondary amines and carbonyl compounds affords cyclic aminals if the amino groups are in suitable positions relative to one another (1,2-, 1,3-, or 1,4-). For example, 1,3-diamines condense readily with aldehydes or ketones to give hexahydropyrimidine derivatives,966 967 and disecpndary ethylenediamine derivatives give imidazolidines.968... 

Both the biosynthesis and chemical synthesis are based on a Mannich condensation of a -phenylethyl-amine derivative with a carbonyl component (Fig.). Depending on the latter, the substituent at Cl can be H-, CH3- or an isoprenoid residue. Several molecules of A. a. can be linked to form oligomers by phenol oxidation, as in pilocereine. As secondary alkaloids, cacti also produce derivatives of p-phenylethylamine, e. g. hordenine and mescaline. 

The a-addition of an iminium ion and the conjugate base of a carboxylic acid to an isocyanide, followed by spontaneous rearrangement of the a-adduct to yield an a-aminocarboxamide derivative. Carbonyl compounds and amines, or their condensation products, serve as precursors to the iminium ion. The nature of the product depends primarily on the acid component ... 

In the aldol reaction, an enolate ion attacks the carbonyl group of an aldehyde or ketone (Section 18-5) to furnish a j8-hydroxycarbonyl product. A process that is quite analogous is the Mannich reaction. Here, however, it is an enol that functions as the nucleophile and an iminium ion, derived by condensation of a second carbonyl component with an amine, as the substrate. The outcome is a j8-aminocarbonyl product. 

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. 

Chapter 8 - It was earned out some conversions of 5-acetyl-2-ethoxycarbonyl-3-p-nitrophenyl indole functional groups, particularly by reduction of nitrogroup was obtained corresponding amine and its condensation products with carbonyl compounds, mono and diacetyl derivatives. 

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). 

The l-chloro-2,2-dibromocyclopropanes 164 similarly undergo the nickel-carbonyl-induced ring-opening carbonylation with an amine or an alcohol to give the / ,y-unsaturated carboxylic acid derivatives 165 and the dicarboxylic acid ones 166 [84]. The mechanism described above appears to be operating this is supported by the four-component condensation to 167. (Scheme 61 and 62)... 

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 ... 

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