Catalytic reactions involving carbonyls

Recently, we have shown that acid faujasites oan catalyze reactions involving carbonyl groups in the liquid phase and at moderate temperatures, and have observed that physicochemical modifications on the Y zeolite influence their catalytic activity (refs. 1-4). In this context, little information is currently available concerning the use of other acidic large pore zeolites, especially with Beta (p) struoture, as acid catalysts in... 

In conclusion, we have shown that due to the diffusional problems, monodirectional large pore zeolites are very inefficient to perform bimolecular reactions involving carbonylic reagents in the liquid phase. By contrast, catalysis by tridirectional Y and fl zeolites show similar features, with a high catalytic activity which increases with the acid strength of the acid sites. 

Carbonylation of the parent acetylene via stoichiometric or catalytic reactions involving transition-metal carbonyl complexes has been extensively studied. Various types of carbonylation reactions of acetylene were discovered. In 1968, Pino et al. [30] reported on the synthesis of hydroquinone via a Ru3(CO)12-cat-alyzed carbonylation of acetylene with H2 or H20. The product formally consisted of two molecules of acetylene and CO, and one molecule of H2 (Eq. 14). To achieve a good yield of hydroquinone, the H2 pressure must be kept under... 

Many catalytic reactions involving CO are promoted by halide ions, especially iodide (cf. methanol carbonylation, Section 22-7). For example, in... 

Catalytic Reactions Involving Cobalt Carbonyl Hydride Complexes... 

Another catalytic reaction involving nickel involves the carbonylation of biphenylene [38]. Heating a THF-dg mixture of (dippe)Ni(CO)2 at 95 °C with Sequiv of biphenylene under 1 atm of CO resulted in the catalytic formation of fluorenone. The proposed mechanism can be seen in Scheme 6.7. The first step is the reversible loss of CO from (dippe)Ni(CO)2. This gives the 14-electron complex (dippe) Ni(CO), to which C-C bond cleavage of biphenylene and CO insertion into the... 

The TT-allyl complex thus generated is of prime interest since its reactivity toward nucleophiles can provide a catalytic route to a whole class of molecules. This feature was essential for the discovery of catalytic reactions involving the acylpalladation of allenes as a key step. First, y-allenyl alcohols react with aryl halides under carbonylative conditions at 65 °C to form furans in a 24-89% yield range, typically 50-89% yields (Scheme... 

The use of chiral bis(oxazoline) copper catalysts has also been often reported as an efficient and economic way to perform asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines with conjugated dienes [81], with the main focus on the application of this methodology towards the preparation of biologically valuable synthons [82]. Only some representative examples are listed below. For example, the copper complex 54 (Scheme 26) has been successfully involved in the catalytic hetero Diels-Alder reaction of a substituted cyclohexadiene with ethyl glyoxylate [83], a key step in the total synthesis of (i )-dihydroactinidiolide (Scheme 30). 

The majority of catalytic enantioselective allylation reactions involve the chiral Lewis-acid-catalysed additions of allylsilanes or allylstannanes to carbonyl compounds. Monothiobinaphthol has been used by Woodward et al. as a chiral promoter in the enantioselective catalytic allylation of aryl ketones with impure Sn(allyl)4, prepared from allyl chloride, air-oxidised magnesium and SnCl4. Therefore, the allylation of arylketones in these conditions was achieved very efficiently, since the corresponding allylic alcohols were formed in... 

Coupling of organostannanes with halides in a carbon monoxide atmosphere leads to ketones by incorporation of a carbonylation step.249 The catalytic cycle is similar to that involved in the coupling of alkyl or aryl halides. These reactions involve Reactions involving a migration of one of the organic substituents to the carbonyl carbon, followed by... 

Some reactions of carbonyl hydrides will be illustrated in Chapter 22. Such species are involved in catalytic processes in which metal carbonyls function as hydrogenation catalysts. Generally carbonyl hydrides are obtained by acidifying solutions containing the corresponding carbonylate anion or by the reactions of metal carbonyls with hydrogen. The following reactions illustrate these processes ... 

This catalytic system was very flexible because by simple modification of the reaction conditions it was possible to prepare oxidized polymers with the desired level of carboxyl and carbonyl functions. No waste was formed because the process did not involve any acids, bases or buffer solutions. The incipient wetness process is very easy to scale up. Hydrophilic starch was prepared in batches of 150 L and incorporated successfully in paint formulations. Good results were also obtained with in vitro and in vivo tests for cosmetic formulation. Interestingly, this is a rather unique example of a heterogeneous catalytic process involving a soluble catalyst and a solid substrate. 

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