Indium catalysis addition

An interesting bifunctional system with a combination of In(OTf)3 and benzoyl-quinine 65 was developed in p-lactam formation reaction from ketenes and an imino ester by Lectka [Eq. (13.40)]. High diastrereo- and enantioselectivity as well as high chemical yield were produced with the bifunctional catalysis. In the absence of the Lewis acid, polymerization of the acid chloride and imino ester occurred, and product yield was moderate. It was proposed that quinine activates ketenes (generated from acyl chloride in the presence of proton sponge) as a nucleophile to generate an enolate, while indium activates the imino ester, which favors the desired addition reaction (66) ... 

Two classes of promoter have been identified for iridium catalysed carbonylation (i) transition metal carbonyls or halocarbonyls (ri) simple group 12 and 13 iodides. Increased rates of catalysis are achieved on addition of 1-10 mole equivalents (per Ir) of the promoter. An example from each class was chosen for spectroscopic study. An Inis promoter provides a relatively simple system since the main group metal does not tend to form carbonyl complexes which can interfere with the observation of iridium species by IR. In situ HP IR studies showed that an indium promoter (Inl3 Ir = 2 1) did not greatly affect the iridium speciation, with [MeIr(CO)2l3] being converted into [Ir(CO)2l4] as the batch reaction progressed, as in the absence of promoter. 

Condensation reactions remain popular for the synthesis of quinolines <2006JOC6592>. Some modern variations on these classic reactions include an example of a solventless system, and the use of indium(m) chloride on silica gel under microwave conditions (Equation 160) <2003T813>. These fast, clean, high-yielding reactions gave aromatized products under indium(m) catalysis after a typical Michael addition of aniline to vinyl ketone. 

A solventless synthesis of substituted quinolines occurs when anilines are reacted with alkyl vinyl ketones in the presence of indium(III) chloride on silica gel and with microwave radiation <03T813>. The mechanism proposed involves Michael addition of aniline to the vinyl ketone followed by cyclization and aromatization under the catalysis of InClj/SiOj. The reactions are fast, clean, and high-yielding. 

The addition of carbon nucleophiles to alkynyl-substituted oxiranes has been reviewed <2002CUOC539>. The reaction between indoles and oxiranes occurs readily under catalysis using indium(iii) bromide <2002JOC5386>. A related process involves solid-state activation using silica gel to promote the reaction <2005JOC3490>, or... 

Michael addition of the aromatic amines to the vinyl ketones followed by subsequent cyclization and aromatization under catalysis by silica gel impregnated with indium(III)chloride has been successfully achieved under MWI to give the corresponding quinolines. Conventional heating produced polymerization of the vinyl ketones that drastically reduced the yield (00TL531). Thus, quinolines 273 were prepared in 55-87% yields by reacting anilines 271 with alkyl vinyl ketones 272 by irradiation in an MW oven for 5-12min (Scheme 57). 

Incorporation of electroactive components often improves performance of electrochemical sensors. Ferreira et al. exploited the LbL technique to produce sensitive and stable glucose biosensors by the immobilization of GOD onto an indium tin oxide (ITO) substrate modified with a Prussian Blue layer [213]. The high sensitivity was attributed to the ultrathin nature of the LbL film in addition to the low operating potentials that could be used due to the efficient catalysis of H2O2 produced in the... 

Schutze, F.-W. Berndt, H. Richter, M. Lucke, B. Schmidt, C. Sowade, T. and Grunert, W., Investigation of indium loaded zeolites and additionally promoted catalysts for the selective catalytic reduction of NO by methane, Studies in Surface Science and Catalysis, 135(Zeolites and Mesoporous Materials at the Dawn of the 21st Century), 1517-1524 (2001). 

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