Indium catalyst

Recently, on the basis of the Markovnikov addition of water to alkynes, Trost et al. developed a three-component addition reaction of terminal alkynes, water, and methyl vinyl ketone, affording 1,5-diketones in DMF/water in the presence of ruthenium and indium catalysts (Eq. 4.38). 

Unlike previous alkyne-aldehyde additions [23], the generation of an alkynyl carbanion is unlikely owing to the large pK, difference between the terminal acetylene and the solvent water [24]. A mechanism was proposed involving the simultaneous activation of the C-H bond of alkyne by the ruthenium catalyst and the aldehyde carbonyl by the indium ion. The ruthenium intermediate then underwent Grignard-type addition followed by an in situ hydrolysis in water to give the desired carbonyl addition product and regenerated the ruthenium and indium catalysts to catalyze further reactions (Fig. 3). 

Scheme 10 Use of asymmetric indium catalysts in organic synthesis...

Direct and efficient organic s5mthesis using indium catalysts, particularly, Friedel-Crafts alkylation of indoles with allylic or benzytic alcohols 07Y99. 

A variety of reactions can be carried out in an aqueous enviromnent given the right choice of catalyst. Water is an extremely attractive solvent choice. Allylation of 1,3-dicarbonyl compounds, for example, is efficiently promoted in water using an indium catalyst (Eq. 10-14). 

Kumar, R. R., Rao, K. N., and A. R. Phani. 2012b. Growth of shicon nanowires by electron beam evaporation using indium catalyst. Materials Letters 66 110-112. 

Lyu KL, Gaidi NA, Gudkov BS, Kostyukovskii MM, Kiperman SL, Podklenova NM, Kogan SB, Bursian NR (1986) Investigation of the kinetics and mechanism of the dehydrogenation of isobutane on platinum and platinum-indium catalysts. Kinet Katal 27 1371-1377... 

Indium salts also exhibited good catalytic activity in a reductive aldol reaction. For example, the silane-promoted diastereoselective reductive aldol reaction has been established by using InBra as a catalyst (173). In their report, the syn-selectivity obtained by an indium catalyst is higher than that of any other... 

Indium catalysts have proven to be very mild catalysts. Reaction of Alder-Ene adduct 140 with aldehydes 141 were proposed to go through an oxonium intermediate 143 to provide the major isomeric product shown 142. ... 

A beautiful example of the synthesis of coiled carbons made by using Fe(CO)5 has been reported by Hou et al. [30]. In that study, the authors found that coiling was influenced by the carbon source (toluene, pyridine). Surprisingly no N-doped coils were observed when pyridine was used as reactant. Many types of helical carbons are known and are formed by the floating catalyst route either by the catalytic pyrolysis of polyethylene or through the use of tin and indium catalysts [30]. 

D. Pierre and M. Jean, Reforming process using platinum-indium-thallium or indium catalyst, US 3871995 A, 1975. 

Several p-block compounds have been employed in this acid-amine coupling reaction these include bismuth, indium and antimony. Indium metal has been found useful for the N-formylation of amines. This reaction requires only 10 mol% indium catalyst and can be used for formic acid reactions with amino alcohols resulting in no side reaction on the alcohol terminus. Electron-rich triarylbismuthanes have been reported to couple carbo>ylic acids to amines within reaction times of 12 hours. In numerous cases, high yields were obtained although little amine scope is explored and in some cases where hindered carbojq lic acids were used, only starting materials were recovered. ... 

In manufacturing, this transformation requires forcing conditions such as high temperatures and long reaction times. It is also highly unselective and produces low ratios of amide to undesired side products such as carbo q lic acids, nitriles and other aldehydes. These issues are amplified when scaled up for commercial use. Consequently, catalytic endeavours have resulted in several methods to reduce these problems. Zinc and indium catalysts have been identified for use in this reaction (Scheme 17.35). Both catalysts are effective however, zinc was preferred over indium as it is more cost efficient despite needing elevated catalyst loadings. ... 

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