PdCl2 catalysts

Technically, acetaldehyde is mainly made by the oxidation of ethylene using a CuCl2/PdCl2 catalyst system.. Although some acetic acid is still prepared by the catalytic oxidation of acetaldehyde, the main process is the catalytic oxidation of paraffins, usually -butane. 

An alternative route for TDI is through a liquid-phase carhonylation of dinitrotoluene in presence of PdCl2 catalyst at approximately 250°C and 200 atmospheres ... 

Efficient acetalization of alkenes bearing various EWG with an optically active 1,3-diol 72 proceeds smoothly utilizing PdCl2. CuCl, and 02 in DME to give the 1,3-dioxane 73[[ 13], Methacrylamide bearing 4-t-butyloxazolidin-2-one 74 as a chiral auxiliary reacts with MeOH in the presence of PdCl2 catalyst... 

Arylthallium bis(trifluoroacetates) (see 2-22) can be carbonylated with CO, an alcohol, and a PdCl2 catalyst to give esters 387... 

Perhaps more surprisingly, [Pd(OAc)2] and PdCl2 could be used in just the same way and, since no phosphine was added, constituted a ligand-free system. For [Pd(OAc)2], adding extra acetate, in the form of NaOAc, led to an increase in the rate, but a decrease in selectivity, resulting in the formation of 5% of the cis-cinnamate. With PdCl2 catalyst decomposition was evident during the reaction. 

Nitrogen-containing heterocycles have been prepared in a similar manner [98]. In this case, both aliphatic and aromatic Ts-protected amines cyclize to yield 5-membered heterocycles with 5mol% (IMes)Pd(02CCF3)2(0H2) (51) as the catalyst (Scheme 11). The corresponding PdCl2 catalyst, 41, is completely inactive, whereas the (IMes)Pd(OAc)2(OH2) complex is comparable to 51. The reaction proceeds most effectively when cocatalytic quantities (10-20 mol %) of acetic acid are present. Under these conditions, the reaction is even successful with ambient air as the source of dioxygen. 

C2H4 and 02 into solution of CuCl2 containing PdCl2 catalyst 26, 83... 

This reaction manifold has been heavily exploited in the assembly of indoles and benzofurans [2]. For example, Taylor and McKillop reported in 1985 that ortho-alkynyl substituted anilines 1 can undergo cyclization in the presence of PdCl2 catalysts to... 

Iron(III) chloride and Fe203 promote PdCl2 catalysts containing an heterocyclic base and sometimes M0O3 in the carbonylation of DNT and PhN02 to form isocyanates [161]. However, a similar activating effect of the steel reactor walls was also observed. Iron(III) prevented the reduction of... 

In 2011, Lu et al. reported that the oxidative formal [2 + 2+1] cycloaddition of 1,8-dialkynylnaphthalenes 96 with primary amines 104 proceeds in dimethyl sulfoxide (DMSO) in the presence of PdCl2 catalyst and EtsN to afford fused pyrroles 98 (Scheme 6.27) [39]. In general, the use of aromatic amines afforded the corresponding pyrroles in higher yields than aliphatic amines. In this oxidative formal [2 + 2+1] cycloaddition, DMSO acts as an oxidant. 

Fig. 8.28 Cascade reaction combining a secondary amine and a PdCl2 catalyst. (From P.-F.Xu, J.-B. Ling, Multiple-catalyst-promoted cascade reactions, in P.-F.Xu, W. Wand (Eds.), Catalytic Cascade Reactions, Wiley, New York, 2014, p. 363. Copyright 2014 Wiley).

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