Amidation rhodium catalysis

Allylamines cyclize readily with a dicobalt octacarbonyl catalyst (equation 55).1,2 Rhodium catalysis generally allows the carbonylative cyclization to be carried out under milder conditions.86 Application of this reaction to unsaturated amides yields the corresponding imides, the best yields arising when R1 = H and R2 = allyl (equation 56).I>2... 

Padwa and Prein presented an extensive experimental and theoretical study of the 1,3-dipolar cycloaddition reactions of isomunchnones with olefinic dipolaro-philes. The a-diazo carbonyl isomunchnone precursors were synthesized in the usual fashion from amides and diazoethylmalonyl chloride. For example, isomunchnone 457 was readily generated from 456 using rhodium catalysis to form... 

Hydration of nitriles providing carboxamides is usually carried out m strongly basic or acidic aqueous media - these reactions require rather bars conditions and suffer from incomplete selectivity to the desired amide product. A few papers in the literature deal with the possibihty of transition metal catalysis of this reaction [28-30]. According to a recent report [30], acetonitrile can be hydrated into acetamide with water-soluble rhodium(I) complexes (such as the one obtained from [ RhCl(COD) 2] and TPPTS) under reasonably mild conditions with unprecedently high rate... 

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. 

The first bisphosphine calixarenes that have been used in catalysis are di(amide)-phosphine hybrids calix[4]ar-ene. Reaction of [RhCl(norbornadiene)]2 with these calixarene derivatives gave an organometallic complex whose norbornadiene-rhodium moiety lies above the cavity defined by the four substituents of the calixarene and between the two amide functionalities. This complex was applied in the hydroformylation reaction of styrene. The rather low reaction rate observed (7.5 turnovers per Rh per hour) has been attributed to a partial encapsulation of the metal center preventing the approach of the substrate. Indeed, the metal center may be viewed as located in a hemispherical ligand environment. 

Nitriles may be hydrated to amides by using acid or base catalysis and vigorous heating. This hydration may be accomplished under neutral anhydrous conditions using acetaldoxime and a rhodium catalyst, which leaves other functionality intact (Eq. 6.13) [19]. 

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