Aminocarbonylation advantage

Pd-catalyzed carbonylation of heteroaryl halides provides a quick entry to heteroaryl carbonyl compounds such as heteroaryl aldehydes, carboxylic acids, ketones, esters, amides, a-keto esters and a-keto amides. In addition, Pd-catalyzed alkoxycarbonylation and aminocarbonylation are compatible with many functional groups, and therefore, are more advantageous than conventional methods for preparing esters and amides [78],... 

The present F C reaction proceeded through the in situ generation of aliphatic imines that were delivered via the protonation of the enecarbamates by the phos phoric acid catalyst (Figure 3.4). Phosphoric acid functioned as an efficient catalyst for the dual transformation that involved the in situ generation of imine and the enantioselective carbon carbon bond formation with indole. This protocol offers the distinct advantage of generating in situ unstable aliphatic imines from storable and thus easily handled enecarbamates, and hence is applicable to other organic transformations. In fact, Terada et al. applied the present method to an enantiose lective direct Mannich reaction [51]. The method provides an efficient pathway to p alkyl P aminocarbonyl derivatives in optically active forms. 

In our discussion, many calixarens have been mentioned in number of chemical reactions as catalyst, however out of these, quaternary ammonium-terminated calixarenes calix[4]arene 4 and calix[6]arene 2 catalysts were used in one-pot Mannich reaction of benzaldehyde, acetophenone and aniline in aqueous media to produce p-aminocarbonyl compounds (see Fig. 27.7) [19]. These calix[n]arene catalysts emphasized not only the high catalytic activity but also have an outstanding reusability with high yield, at low loading amoxmt. Advantages of that were, short reaction times, high yields, and easy work-up that make them great candidate for Mannich-type reactions (see Table 27.5). 

The other advantage of aminocarbonylation involves the great variety of nucleophiles that can effectively be applied as reactants. Beside the commonly used primary and secondary amines, these include propargylamine in the synthesis of an intermediate of 8-epi-griseoviridin [105], arylamines, and heteroarylamines in the synthesis of gonadotropine-releasing hormone antagonists [104], substituted hydrazine derivatives [97], hydrazides [98], amino crown ethers [99], and amino acids [94,106]. Even sulfonamides were shown to be able to participate as nucleophiles in microwave-accelerated carbonylation in the presence of Mo(CO)g as the carbonyl source [107]. 

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