Nitriles ligand reactions

Kostic et al. recently reported the use of various palladium(II) aqua complexes as catalysts for the hydration of nitriles.456 crossrefil. 34 Reactivity of coordination These complexes, some of which are shown in Figure 36, also catalyze hydrolytic cleavage of peptides, decomposition of urea to carbon dioxide and ammonia, and alcoholysis of urea to ammonia and various carbamate esters.420-424, 427,429,456,457 Qggj-jy palladium(II) aqua complexes are versatile catalysts for hydrolytic reactions. Their catalytic properties arise from the presence of labile water or other solvent ligands which can be displaced by a substrate. In many cases the coordinated substrate becomes activated toward nucleophilic additions of water/hydroxide or alcohols. New palladium(II) complexes cis-[Pd(dtod)Cl2] and c - Pd(dtod)(sol)2]2+ contain the bidentate ligand 3,6-dithiaoctane-l,8-diol (dtod) and unidentate ligands, chloride anions, or the solvent (sol) molecules. The latter complex is an efficient catalyst for the hydration and methanolysis of nitriles, reactions shown in Equation (3) 435... 

Many of the reactions which have been reported for carbonyl compounds (hydration, alcoholysis, aminolysis, etc.) are also shown by co-ordinated nitrile ligands. The reaction of a nucleophile with a nitrile is a two-stage process, which may involve one or two molecules of the incoming nucleophile (Fig. 4-6). 

With the objective of obtaining palladium chelates, the ligand-exchange reactions with the participation of nitrile complexes of Pd halides are widely used. Thus, coordination units PdN4 and PdN202 are formed as a result of the transformation (3.109) with participation of 2-tosylamino(hydroxy)phenylbenzazoles [282] ... 

Hindered tertiary nitriles can be hydrolyzed under neutral and mild conditions to the corresponding amides by using the above-mentioned platinum(II) catalysts with dimethylphosphine oxide or other SPOs as ligands. Nitriles containing acid- or base-sensitive groups are converted with unprecedented selectivity by this procedure. The ratio of the concentration of the catalyst to that of the reactant can be as low as 0.5 mol%. Reactions are carried out at 80 °C but take place even at room temperature. 

Ligand-exchange reactions leading to chelates of hetaryl Schiff bases involve those with acetylacetonate (Equation (22a)) and nitrile (Equation (22b)) conmlexes (where A = CH, N R = Aik, Ar, cyclo-CiHi = Aik, Ar, Het R = Me, Ph). 

Allyltetrazoles are selectively prepared by three-component coupling of allyl carbonate, TMS azide and nitrile. Reaction of dimethylcyanamide (231) afforded 2-allyl-4-(dimethylamino)tetrazole 232 using TFP (1-3) as a ligand. 7r-Allylpalla-dium tetrazole is the proposed intermediate [84]. 

The exceptional strength of the metal-cyanide linkage makes it challenging to develop catalytic processes that involve excess CN" as reagent. The Pd-catalyzed cyanation of aryl halides discussed in Chapter 19 to form aryl nitriles initially suffered from the formation of catalytically inactive cyanide complexes containing multiple CN" ligands the reaction has been improved by the use of ZnfCN) or Kj[Fe(CN)J as the CN" source. ... 

The reaction tolerates a wide range of functional substituents and allows use of alkenes, alcohols, amines, esters, halogens, and nitriles. Reactions of 1,6-octadiynes with such monoynes results in ortho- and mefia-substituted derivatives. Regioselectivity of the reaction is controlled by the choice of the ligand. Thus, the interaction of diyne 2.10 and monoyne 2.11 in the presence of dppe [l,2-bis(diphenylphosphino)ethane] yields mainly the meta-isomer 2.12 (selectivity 88%), whereas in the presence of dppf [1,1 -bis(diphenylphosphino)ferrocene] the yield of ortho-isomerlA3 reaches 82% [39] (Scheme 2.5). 

Kwiatek and Seyler were the first to report that many organopenta-cyanides, when treated first with acid and then with alkali, liberate nitriles 110). This reaction occurs with unsubstituted primary and secondary alkyl, benzyl, vinyl, and phenyl complexes, while allyl, 2-oxo-, 2-hydroxy-, and 2-alkoxy complexes simply release the organo-ligand on treatment with acid, and 1-cyanoalkyl and a-pyridyl complexes are stable 105) (see also Table IV). The yield of nitrile is usually far from quantitative and is... 

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