Alkylation indium bromide

Indium bromide was found to catalyze the formation of polyhydroxyl pyrrole 34 from pyranone 33 and aniline. The reaction is proposed to proceed via the ring expansion of an iminocyclopropane followed by intramolecular attack of the resulting oxonium species. Pyrrole 34 is generated in one-pot in good to excellent yields and can be obtained with either an N-aryl or AT-alkyl group (130L3852). 

Indium-mediated coupling of sulfonyl chlorides with alkyl bromides in water readily generates sulfones.89 Sulfones can also be obtained via... 

Intramolecular cyclization of tethered phenyl ketones (58 X = Br, SiMe3) show contrasting stereochemical outcomes for indium catalysis of the alkyl bromides and fluoride ion-induced reaction of the allylsilanes. The reactions thus allow complementarity in product diastereoselectivity, and the difference appears to be related to an... 

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). 

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... 

Sequential nucleophilic and electrophilic alkylations of 1,3-dicarbonyl compounds with a trimethylenemethane zwitterion equivalent lead to [3 + 2]-annulation. The nucleophilic carbonyl alkylation step has been carried out via an indium-mediated allylation in water (Equation (30)).200 Indium-mediated allylation of a-chlorocarbonyl compounds with allyl bromides in aqueous media gives the corresponding homoallylic chlorohydrins, which can be transformed to allyloxiranes (Equation (31)).201 Allylation of the G3 position of the cephem nucleus has been accomplished by indium-mediated allylation reaction in aqueous media (Equation (32)).202... 

Dichloroindium hydride (Cl2InH), generated by the reaction of InCl3 with tributyltin hydride, is also successfully used for the reduction of carbonyl compounds and for the debromination of alkyl bromides.366 This reductant has features such as the chemoselective reduction of functionalized benzaldehydes, chelation-controlled reduction of benzoin methyl ether, and 1,4-reduction of chalcone. The stable carbene and tertiary phosphine adducts of indium trihydride, InH3 CN(Mes)CH=CHN(Mes) and InH3 P(c-G6H11)3, reduce ketones to alcohols (Equation (90)).367... 

Reductive alkylation of aromatic nitro compounds is possible. The reaction of nitrobenzene with allylic or benzyl hahdes in the presence of an excess of tin metal in methanol, leads to the A,A -diaUyl or dibenzyl aniline. A similar reaction occurs with nitrobenzene, allyl bromide, and indium metal in aq. acetonitrile. 

Butenylcyclopropanes. The indium-promoted reaction of enones with allyl bromide gives cyclopropane derivatives in which two C3H5 units are unified to effect reductive gem-di alkylation of the carbonyl group of the enones, when the initial adducts are treated with LiBr before workup. Otherwise the normal allylation products prevail. 

Scheme 7.9 Alkylation of 1,3-dicarbonyl compounds using allyl bromide or allyl chloride and indium in water.

A new indium subhalide, of composition InBri.jg, is formed as an intermediate in the oxidation of InBr by alkyl bromides. This composition corresponds to In7Brg, and it is tentatively formulated as 6In+(InBrg ). 3Br", since a Raman band at 163 cm is observed, characteristic of InBr -. 

The organogailium halides resemble the aluminium compounds closely. They can be made by redistribution between RjGa and GaClj. Indium reacts very slowly with alkyl bromides and iodides to give mixtures of RlnX and R InX which analyse as RjIn Xj. Melnl can also be made from Ini and Mel at room temperature. Solid Me InCl consists of units stacked one above the other, so that the indium atoms are five coordinate. 

Li and coworkers reported the conjugate addition of alkyl groups to enamides mediated by zinc in aq. NH4CI to generate a -amino acid derivatives (Eq. 4.73). No reaction was observed in the absence of water. Both secondary and tertiary alkyl groups such as linear (2-butyl, 2-propyl, 2-pentyl), cyclic (cyclohexyl, cyclopentyl, cycloheptyl), and bulky ones (tert-butyl) were all transferred to the substrate successfully. Even simple primary iodides and methyl iodide provided the desired products in good yields. Miyabe et al. as well as Jang and Cho reported the addition of alkyl radicals from alkyl iodide to a,p unsaturated ketones, esters, and nitriles mediated by indium in aqueous media. Indium-mediated Michael addition of allyl bromide to l,l-dicyano-2-arylethenes also proceeded well in aqueous medium. ... 

Although in this chapter we shall be restricting coverage to reactions of transition-metal complexes, the phenomenon of oxidative addition is not confined to this type of compound. Such reactions are also well established for non-transition metals—a recently reported example concerns the oxidative addition of methyl bromide to indium(i) bromide to give InBr2Me— and for non-metals, as in the reaction of phosphorus trichloride with chlorine, to cite a very familiar example. Likewise, reductive eliminations are known and studied outside the area of transition-metal complexes. One example has been mentioned in Chapter 1 of Part II of this volume, namely the elimination of alkyl halides from the thallium(iii) compounds TlRXa. ... 

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