Carbonylation, of benzyl alcohol

Lin and Yamamoto described a Pd-catalyzed carbonylation of benzyl alcohols [131]. Thus, under the agency of palladium catalysis and promotion by HI, 3-thiophenemethanol was carbonylated to give 3-thiopheneacetic acid as a major product along with methylthiophene as a minor one. 

Figure 9.7 Carbonylation of benzyl alcohol-catalyzed by tppts/Pd.

In the same way, the biphasic carbonylation of benzyl alcohol (Figure 9.7) was achieved.Phenylacetic acid was obtained in 11% yield, 100% selectivity, and 100% atom utilization. 

Carbonylation of Alcohols - Pd(tppts)3 catalyses the carbonylation of benzylic alcohols to the corresponding phenylacetic acids, in the presence of a Bronsted acid cocatalyst such as H2S04 or p-CH3C6H4S03H in biphasic aqueous/organic media (no organic solvent).305,451 For example, benzyl alcohol was converted to phenylacetic acid (Equation 6) and l-(4-isobutylphenyl)ethanol (IBPE) to ibuprofen (Figure 9). 

Pd/PPh3 complexes catalyse the carbonylation of activated benzyl alcohols such as 4-hydroxybenzyl alcohol whereas they are inactive in the carbonylation of benzyl alcohol.463 In sharp contrast, the water soluble Pd(tppts)3 complex catalyses the carbonylation of benzyl alcohol to phenylacetic acid, equation (6), under mild reaction conditions employing an aqueous/organic two phase... 

Selective carbonylation of HMF was observed to yield 5-formylfuran-2-acetic acid as the sole carbonylation product the only byproduct was 5-methyl-2-furfural (MF). The activity and selectivity were both found to be strongly influenced by the tppts/Pd ratio the maximum efficiency was observed for tppts/Pd = 6. Replacement of tppts by ligands containing fewer sulfonate groups, e.g., tppds or tppms, led to a dramatic drop in the catalytic activity. Furthermore, it was found that the selective carbonylation of benzyl alcohol to phenylacetic acid also took place in the presence of the catalyst (84). 

The general reaction scheme used to describe methanol carbonylation has been extended to include the carbonylations of benzyl alcohol (28), ethanol (24a, 29,30) and I-propanol (24a, 31). In fact, the study with the last system has made it necessary to expand the original scheme to account for the production of mixtures of isomeric products (vide infra). 

The salt production can be circumvented by performing the selective Pd/ tppts-catalysed carbonylation of benzyl alcohol in an acidic aqueous biphasic system (Fig. 1.36) [106]. This methodology was also applied to the synthesis of ibuprofen (see earlier) by biphasic carbonylation of l-(4-isobutylphenyl)ethanol [107] and to the biphasic hydrocarboxylation of olefins [108]. 

Carbonylation of Benzyl Alcohol to Phenylacetic Acid Manufacture of Ibuprofen... 

This type of oxidative addition involving the carbon-halogen bond cleavage may be involved in other catalytic processes using alcohols in the presence of hydrogen halide. For example, in the carbonylation of benzyl alcohol in the presence of HI, phenylacetic acid can be catalyfically produced in the presence of aPd(O) complex (Eq. 1.5) [25]. 

Larock and Fellows reported on the thallation-carbonylation of benzyl alcohols in 1982 [241]. Thallium (III) trifluoroacetate was used for the ortho-thallation of... 

Catalytic carbonylation of aryl methanols has been less explored (Scheme 10). Direct carbonylation of benzyl alcohol to phenyl acetic acid has been reported,... 

Synthesis of Aromatic Esters.—Esters and amides of phenylacetic acids are produced by the cobalt-carbonyl-catalysed carbonylation of benzyl alcohols. ... 

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