Amidation, using supported palladium

Figure 4.30 Amidation of aryl halides using a supported palladium catalyst...

A novel use ofthe salt [BMIM][PF6] is to enhance microwave absorption and hence accelerate the rate of a reaction. Ley found that [BMIM][PF6] enhanced the rate of the microwave promoted thionation of amides using a polymer supported thionating agent [304]. Hardacre et al. have developed a protocol for the synthesis of deuterated imidazoles and imidazolium salts [305]. The procedure involves the platinum- or palladium- catalyzed deuterium exchange of 1-methyl-d -imidazole with D2O to give 1-methylimidazole-d , followed by reaction with a deuterated alkyl halide. 

Starting with bromoallenes 133, nucleophilic substitution supported by the use of cuprous cyanide lead to cyanoallenes of type 134 (Scheme 7.22) [126, 131, 181]. Pro-pargyl precursors and also cumulenes of type 133 can be utilized for palladium-catalyzed aminocarbonylation to give allenic amides 135 (cf. Section 7.2.6) [182]. 

A highly stereoselective synthesis of ( )-gephyrotoxin (20) has been carried out. An interesting feature is the reversal of the stereochemical course of the hydrogenation of the vinylogous amide (21) by the use of an alumina support. Hydrogenation of (21) over palladium on charcoal gives the amino-alcohol (22) as... 

The polymeric imide could then be reacted with primary amines or ammonia to form ammonium salts for a subsequent reactions with a carboxylic acid in the presence of a coupling reagent. It could then be converted to amides or functionalized as a uranium salt for use as polymer-supported peptide coupling. In addition, the anhydride was also reacted with di(2-pyrldyl)methylamine and formed a recoverable palladium catalyst for cross-coupling reactions that could take place in water. 

In 2006, Griebenow and coworkers [31] described the palladium-catalyzed a-arylation of ketones on a solid support using modified Buchwald-Hairtwig reaction conditions. The coupling of immobilized 4-bromobenzamide (prepared from polystyrene Rink amide resin and 4-bromobenzoic acid chloride) with several aromatic, heteroaromatic, and aliphatic ketones was investigated. 

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