Indium metal, reactions

Sulfates. Indium metal and its oxides dissolve in warm sulfuric acid to give a solution of the trisulfate [13464-82-9], In2(S0 2- It is a white, crystalline, deUquescent soHd, readily soluble in water that forms double salts with alkaLi sulfates and some organic substituted ammonium bases. Concentration of the acidified trisulfate solution produces indium acid sulfate crystal [57344-73-7], In(HS0 2> other reaction conditions give basic sulfates. 

As shovm in Eq 6 59, Rapoport has prepared sinefungin, nucleoside andbiodcs, via nitro-aldol reaction, dehydradon, and reducdon v/iihZn in acetic acid fi-Niiro styrenes are selecdvity reduced to the corresponding oximes by indium metal in aqueous methanol under neutral conthdons ... 

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

Although not formally the enamine synthesis, reaction of an enamine with methyl hromoacetate in the presence of indium metal leads to a-aUcylation R2N-CH=CHR R2N-CH(R )CHR. ... 

The reaction can also be carried out using indium metal. Under these conditions InCl3 is presumably generated in situ.135... 

One notable result is the treatment of 2-hydroxy cyclic ether analog, 2-deoxy-D-ribose with aniline in water catalyzed by InCl3 to afford the novel tricyclic tetrahydroquinoline compounds (Eq. 12.60). The reaction can also be catalyzed by recoverable cation-exchange resin instead of indium chloride.132 By using a stoichiometric amount of indium metal, a domino reaction of nitroarenes with 2,3-dihydrofuran generates the same products. 133... 

Alkylation products 173 of iminochromenes 159 were synthesized using allyl bromides 174, Nal, and metallic indium. The indium-meditated reaction is accompanied by a complete allyl rearrangement (08SL2791) (Scheme 64). 

In this context, Yadav and coworkers have recently developed a mild and efficient procednre for the selective rednction of / -nitrostyrenes 22 to oximes 23 using indium metal in aqueous methanol under neutral reaction conditions (Scheme 19). Similarly, a-alkoxy oximes 24 are formed in good yields by the treatment of nitroolefins with metalhc indium and trimethylsilyl chloride in anhydrous methanol (Scheme 19). 

The malodorous aqueous phase from the work-up of reaction A was treated with commercial bleach before disposal. Metallic indium from reaction B was treated with coned HCI and diluted before disposal. 

Indium(III) cyanide is best prepared from InOI and cyanogen, although other methods have been described.52 An ammonia adduct of In(CN)3 may be formed in the reaction between Hg(CN)2 and indium metal in liquid ammonia, but no other derivatives have been reported. 

A number of reactivity studies have been performed on 6 and 8 and indicate a strongly polar (if not ionic) Mn—E bond Mn "—E,+ (E = In, Tl). Thus heterolytic bond dissociation occurs in polar ligating solvents such as MeCN or DMF, and halogens, hydrogen halides, and alkyl halides readily add across the metal-metal bond in a manner consistent with the polarity described above (13,13a,18). In the thallium example, however, the reactions are generally more complicated and result in T1(I) salts [e.g., Eq. (3)], and metal exchange reactions are also more facile, e.g., the synthesis of 6 from 8 and indium metal. In general, therefore, the chemistry of 6 and 8 is consistent with predominantly ionic behavior. 

All the above complexes, 9-12, are isolated from reactions involving gallium or indium metal and [Mn2(CO)10] or [Re2(CO)10] in an autoclave, although 11 has also been obtained by thermolysis of 6. Some details on the reactivity of 11 toward phosphonium halides (23) have been reported and indicate formation of the halo-indium complexes [PPh4]2[Mn2(CO)8 /j-lnX2 2]. A higher nuclearity cluster has also been obtained in the reaction of [Re2(CO)10] with indium metal, viz. [Re4(CO)12 /i3-InRe(CO)5 4], 13 (24,24a). This consists of a central tetrahedral Re4(CO)12 core with each face capped by an InRe(CO)s fragment as shown in Fig. 4. 

Finally, we note a report of the synthesis and structure of a mixed transition metal-indium complex containing iron and manganese derived from the reaction between [Hg Mn(CO)5 2], [Fe(CO)5], and indium metal, viz. [ Fe(CO)4 2 /i-InMn(CO)5 2], 16 (27) (see Fig. 5). This complex is structurally similar to the manganese-indium complex 11 with each Mn(CO)4 fragment replaced in 16 by an Fe(CO)4 moiety. The increase in the electron count by two has been assumed to account for the absence of a Fe—Fe bond in 16 in contrast to the suggested presence of a corresponding Mn—Mn... 

A three-component reaction based on the umpolung of re-allylpalladium (II) complexes indium metal was reported by Grigg and co-workers (Scheme 8.31) [74]. In this reaction, the electrophilic nature of the n-allyl palladium species generated from aryl halides and allenes is reversed by transmetallation with indium metal. The resultant nucleophilic allylindium reagent subsequently adds to the third component - aldehyde [75] or imine [76] - to give the corresponding homo-allylic alcohol 64 or amine 65 respectively. 

Acetyl ligands, in niobium complexes, C-H BDEs, 1, 298 Achiral phosphines, on polymer-supported peptides, 12, 698 Acid halides, indium compound reactions, 9, 683 Acidity, one-electron oxidized metal hydrides, 1, 294 Acid leaching, in organometallic stability studies, 12, 612 Acid-platinum rf-monoalkynes, interactions, 8, 641 Acrylate, polymerization with aluminum catalysts, 3, 280 Acrylic monomers, lanthanide-catalyzed polymerization,... 

Epoxides are deoxygenated with indium metal in the presence of indium(I) chloride or ammonium chloride. It is proposed that the reaction occurs through an SET process with indium as an electron donor.309... 

In indium-mediated reactions, a catalytic use of expensive indium is desirable from an economical standpoint, and it has been achieved in combination with more electron-positive metals. Thus, allylation of aldehydes and ketones, as well as prenylation of 2-chlorobenzoquinone, has been performed by using metallic aluminum or zinc in combination with a catalytic amount of indium(m) chloride.63 Also, allylation of aldehydes and ketones with allyl bromide is carried out with a catalytic amount of indium powder (from 0.01 to 0.1 equiv.) in THF in the presence of manganese and chlorotrimethylsilane as the reducing and oxophilic agents, respectively (Scheme 2). 64,65... 

The coupling reaction of a-keto esters with allyl, propargyl, and allenyl halides using indium metal in aqueous solvents affords a-hydroxy-y,<5-unsaturated esters (Equation (28)).197,198 1,3-Dicarbonyl compounds undergo efficient carbonyl allylation reactions in an aqueous medium through a Barbier-type reaction (Equation (29)). The reaction is general and a variety of 1,3-dicarbonyls has been alkylated using allyl bromide or allyl chloride in conjunction with indium.199... 

The allylation of imines with allylindium reagents in organic solvents gives the corresponding homoallylic amines.251-253 Under solvent-free conditions, the indium-mediated reaction of iV-benzylideneaniline furnishes a mixture of mono-allylated 79 and bis-allylated products 80 (Equation (56)). The bis-allylated product 80 presumably arises via a formation of an iminium salt, which is subsequently attacked by the allylindium nucleophiles. Formation of 80 is entirely suppressed by addition of allyl bromide to indium metal prior to any addition of the imine (Grignard-type reaction).254... 

Treatment of tethered alkyne-allyl halides with indium metal in halogenated solvents affords carbocyclic vinyl halides via a novel atom-transfer reaction. The reactions are operationally facile and proceed smoothly at room temperature even with sub-stoichiometric quantities of indium. Use of a halogenated solvent containing a different... 

The zinc-mediated Reformatsky reaction is one of the classical methods for carbon-carbon bond formation. To date, various main group metals and transition metals have been used for this reaction. Rieke s activated indium powder mediates readily the coupling of ethyl a-bromoacetate and a variety of carbonyl compounds yielding /3-hydroxy esters in good yields (Scheme 87).3 Later, commercially available indium powder has been found to be equally effective for the indium-based Reformatsky reaction in THF.28 This indium Reformatsky reaction is accelerated by ultrasound irradiation (Scheme 88).322,323 Indium(i) iodide also mediates the Reformatsky reaction of aldehydes and ketones to give /3-hydroxy esters, presumably via organoindium(m) diiodide (Scheme 89).27... 

Reaction of phenacyl iodide with indium metal gives 3,4-epoxy-1,3-diphenyl-1-butanone which, on treatment with silica gel, gives 2,4-diphenylfuran and 2,4-diphenyl-4-oxobutanal (Scheme 92). Metallic indium as well as indium(i) iodide mediate the aldol condensation between ce-halo ketone and aldehyde.333... 

The organoindium reagent, prepared from indium metal and bromoacetonitrile, reacts with carbonyl compounds in the presence of chlorotrimethylsilane to give /3-hydroxy nitriles (Scheme 93),336 337 Similarly, indium-mediated coupling of bromoacetonitrile or 2-bromopropionitrile with a variety of aromatic acyl cyanides affords the corresponding aromatic a-cyanoketones in moderate to good yields under mild and neutral conditions (Equation (86)).338 Carbonyl compounds are efficiently transformed into 2,2-dichloro-3-hydroxynitriles by the action of trichloroaceto-nitrile and indium(i) bromide (Scheme 94).339 Bromocyanomethylation of carbonyl compounds is also achieved by the reaction of dibromoacetonitrile and indium(i) bromide.340... 

The direct allylation of aromatic compounds with allylic chlorides is achieved in the presence of a catalytic amount of indium metal. According to the authors, indium is considered to act as a Lewis acid (Equation (101)).399 Trialkylindiums react with acid chlorides to give ketones. When trialkylindiums are treated with air prior to the reaction with acid chlorides, esters are formed (Scheme 121).400 The reaction of cyclopentadienylindium(i) with aldehydes in aqueous media gives mixtures of the isomeric coupling products (Equation (102)).401... 

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