Amides with aldehydes

The term aminoplastics has been coined to cover a range of resinous polymers produced by interaction of amines or amides with aldehydes. Of the various polymers of this type that have been produced there are two of current commercial importance in the field of plastics, the urea-formaldehyde and the melamine-formaldehyde resins. There has in the past also been some commercial interest in aniline-formaldehyde resins and in systems containing thiourea but today these are of little or no importance. Melamine-phenol-formaldehyde resins have also been introduced for use in moulding powders, and benzoguanamine-based resins are used for surface coating applications. 

Reaction of Primary or Secondary Amides with Aldehydes or Ketones... 

Saito, S. Kobayashi, S. Highly Anti-selective Catalytic Aldol Reactions of Amides with Aldehydes, f Am. Chem. Soc. 2006, 128, 8704-8705. 

Examples of the condensation of amides with aldehydes were also known at this time. Roth and Schuster, working in Strecker s laboratory, had prepared benzylidene diacetamide and anisylidene diacetamide by heating the aldehydes with acetamide. Von Richter in 1872 reported that Tawildarow obtained ethylidene diacetamide by heating acetaldehyde and acetamide, and Nencki obtained ethylidene dibenzamide by carrying out a similar reaction in the presence of hydrochloric acid. 

Derivatives of the steroids androstene and pregnene have been transformed directly into A-acyl amino acids by an orthogonal catalysis procedure, utilizing [RhCl(nbd)]2 and Co2(CO)8 (Scheme 11). The rhodium phosphine catalyst (generated in situ in the presence of syn-gas and phosphine) affects hydroformylation of the internal olefin to generate aldehyde. In the presence of Co2(CO)8, A-acyl amino acids are obtained as the major products. An unstable amido alcohol intermediate, formed by reaction of the amide with aldehyde, is proposed to undergo cobalt-catalyzed GO insertion to yield the desired A-acyl amino acid. 

A modification consists of reacting amides with aldehydes and olefins.157-158... 

In another example the MCR of a-aminoacid amides with aldehydes and isocyanides in the presence of a base and subsequent acetic acid treatment was investigated [13]. Based upon a general understanding of the mechanism of the Ugi reaction it was proposed that the Schiff base is formed, followed by the formation of the a-adduct with the isocyanide (Scheme 3.8). This compound was assumed to be the end point of the reaction, and unable to rearrange. 

Base-Catalyzed Reactions of Phosphonomethyl-phosphinates, Bis(phosphonomethyl)phosphinates, and Bis(phosphonomethyl)phosphinic Amides with Aldehydes... 

The same group further developed the asymmetric aldol reaction of A -methoxy-A -methyl-a-isocyanoacetamide (a-isocyano Weinreb amide) with aldehydes (Sch. 25). The reaction of the Weinreb amide 96 with acetaldehyde in the presence of 86c Au(I) catalyst gives the optically active tram-oxazoline 98 (E = CON(Me)OMe R = Me) with high diastereo- and enantioselectivities similar to those of 95 [49], The oxazoline can be transformed into A,0-protected /3-hydroxy-a-amino aldehydes or ketones. 

It is worth emphasising the ease of the reaction of amines and amides with aldehydes, since it explains the need to use purified solvents when dealing with amino acids, peptides and proteins, to avoid such side-reactions. Glutaraldehyde has been used for crosslinking proteins (from the earliest days in the leather industry, too) but it is toxic and therefore less in favour in laboratory work now. 

I. -x n/amides with aldehydes is mediated by Cjtc. r. toluene and then treated with NaH, the... 

The complex of NaGeEt, with SmClj promotes a syn-selective aldol reaction of ketones and amides with aldehydes in the presence of HMPA in THF. The enolization step at 0° is followed by treatment of the aldehydes at -78°. 

Aminoresins or aminoplastics cover a range of resinous polymers produced by reaction of amines or amides with aldehydes [14,46,47]. Two such polymers of commercial importance in the field of plastics are the urea-formaldehyde and melamine-formaldehyde resins. Formaldehyde reacts with the amino groups to form aminomethylol derivatives which undergo further condensation to form resinous products. In contras to phenolic resins, products derived from urea and melamine are colorless. 

For the purposes of this chapter, aminopolymers are defined as polymers formed by the interaction of amines or amides with aldehydes. Of the various polymers of this type which have been investigated, only two are currently of appreciable commercial importance, namely urea-formaldehyde and melamine-formaldehyde polymers. In addition, melamine-phenol-formaldehyde and benzoguanamine-formaldehyde polymers find limited application. In the past there has been some commercial interest in thiourea-formaldehyde and aniline-formaldehyde polymers but these products are now of little importance. The aforementioned polymers form the contents of this chapter. 

Enamides and thioenamides are prepared by similar methods and involve the condensation reaction of the appropriate amides with aldehydes [5] to give... 

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