Reaction of InCl3 with various reducing agents: InCl3-NaBH4-mediated reduction of aromatic and aliphatic nitriles to primary amines

While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reduction of InCl(3) using lithium amino borohydride (LAB) were explored, generation of HInCl(2) from the reduction of InCl(3) by sodium borohydride (NaBH(4)) was also re-evaluated for comparison. The reductive capability of the InCl(3)/NaBH(4) system was found to be highly dependent on the solvent used. Investigation by (11)B NMR spectroscopic analyses indicated that the reaction of InCl(3) with NaBH(4) in THF generates HInCl(2) along with borane-tetrahydrofuran (BH(3)·THF) in situ. Nitriles underwent reduction to primary amines under optimized conditions at 25 °C using 1 equiv of anhydrous InCl(3) with 3 equiv of NaBH(4) in THF. A variety of aromatic, heteroaromatic, and aliphatic nitriles were reduced to their corresponding primary amine in 70-99% isolated yields. Alkyl halide and nitrile functional groups were reduced in tandem by utilizing the reductive capabilities of both HInCl(2) and BH(3)·THF in a one-pot reaction. Finally, the selective reduction of the carbon bromine bond in the presence of nitriles was achieved by generating HInCl(2) via the reduction InCl(3) with NaBH(4) in CH(3)CN or with lithium dimethylaminoborohydride (MeLAB) in THF.     

Direct coupling reaction between alcohols and silyl compounds: enhancement of Lewis acidity of Me3SiBr using InCl3

The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the 13C NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by 29Si NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.     

InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates

A combined Lewis acid catalyst of InCl(3) and Me(3)SiBr promoted the direct use of enol acetates in the coupling with low-reactive silyl ethers, in which functional groups including ketones and aldehydes survived. Sterically hindered silyl ethers such as ROSiEt(3), ROSiPh(3), ROSit-BuMe(2), and ROSii-Pr(3) were also applicable.     

Reexamination of CeCl3 and InCl3 as activators in the diastereoselective Mukaiyama aldol reaction in aqueous media

A search for suitable reaction conditions in Mukaiyama-type aldol condensations activated by CeCl(3) and InCl(3) revealed that the reaction proceeds best in i-PrOH/H(2)O (95:5). Contrary to literature precedent, no reaction was observed in pure water, and the encountered destruction of the starting silyl enol ether can be ascribed to initial hydrolysis of the Lewis acid. As anticipated from the dual parameter (pK(h), WERC value) characteristics of CeCl(3) and InCl(3), the former proved more efficient as Lewis acid-promoter, in terms of reaction speed and yield. Nevertheless, InCl(3) was a superior catalyst during evaluation of the diastereoselectivity of the process. In this regard, determination of diastereoselectivity as a function of time showed that the InCl(3)-catalyzed reaction is irreversible, whereas the CeCl(3)-catalyzed reaction is a reversible process. In both cases, formation of the syn product is kinetically preferred, although DeltaDeltaG(++)273K(InCl(3)) = 1.50 kcal/mol versus DeltaDeltaG(++)273K (CeCl(3)) = 0.38 kcal/mol. Molecular modeling (semiempirical PM3, ab initio HF/3-21G*, hybrid B3LYP/3-21G*, and B3LYP/LANL2DZ) of the diastereoselective aldol reaction promoted by InCl(3) supports a "closed", Zimmermann-Traxler transition state.     

InCl(3)-catalyzed three-component asymmetric Mannich-type reaction in methanol

[reaction: see text] A one-pot InCl(3)-catalyzed Mannich-type reaction was carried out in methanol. High diastereoselectivities and high yields were obtained. In addition, after the reaction was completed, InCl(3) can be recycled and reused without a drop of activity and selectivity.     

Studies on Room Temperature Ionic Liquid Prepared from InCl3—MBIC

The phase diapgram of InCl23-MBIC was constructed by DSC method .A clear,colorless and mobile ionic liquid was obtained and liquid down to 258K ,Both Raman Scattering and ab initio calculations indicate that InCl4 is the predominant anion.     

Skeletal reorganization of enynes catalyzed by InCl3

[reaction: see text] The skeletal reorganization of enynes is achieved by the presence of InCl(3) as the catalyst. The reaction of enynes having a terminal acetylenic moiety proceeds in a stereospecific manner to give 1-vinylcycloalkenes. The reaction of enynes containing an alkyl group on the acetylenic terminal carbon resulted in a new type of skeletal reorganization to give 1-allylcycloalkenes, formation of which involves a double cleavage of the C-C double bond and the triple bond.     

Highly chemoselective reductive amination of carbonyl compounds promoted by InCl3/Et3SiH/MeOH system

A new strategy has been developed for reductive amination of aldehydes and ketones with the InCl3/Et3SiH/MeOH system, which is a nontoxic system with highly chemoselective and nonwater sensitive properties. The methodology can be applied to a variety of cyclic, acyclic, aromatic, and aliphatic amines. Functionalities including ester, hydroxyl, carboxylic acid, and olefin are found to be stable under our conditions. The reaction shows a first-order kinetics profile with respect to both InCl3 and Et3SiH. Spectroscopic techniques such as NMR and ESI-MS have been employed to probe the active and resulting species arising from InCl3 and Et3SiH in MeOH, which are important in deriving a mechanistic proposal. In the ESI-MS studies, we have first discovered the existence of stable methanol-coordinated indium(III) species which are presumably responsible for the gentle generation of indium hydride at room temperature. The solvent attribution was crucial in tuning the reactivity of [In-H] species, leading to the establishment of mild reaction conditions. The system is superior in flexible tuning of hydride reactivity, resulting in the system being highly chemoselective.     

Diastereoselective synthesis of cyclopentanediols by InCl 3/Al mediated intramolecular pinacol coupling reaction in aqueous media

A "green" and practical intramolecular pinacol coupling reaction promoted by InCl 3/Al catalysts in aqueous media has been developed. Under mild conditions, a novel class of polysubstituted cyclopentane-1,2-diols have been obtained with excellent diastereoselectivity.     

InCl3-catalyzed allylic Friedel-Crafts reactions toward the stereocontrolled synthesis of 1,2,3,4-tetrahydroquinolines

Allyl chlorides tethered to an N-aryl moiety readily undergo InCl(3)-catalyzed Friedel-Crafts reactions to furnish highly enantiomerically enriched 1,2,3,4-tetrahydroquinolines with good yields and excellent diastereoselectivity.     

InCl3·4H2O Promoted Green Preparation of Xanthenedione Derivatives in Ionic Liquids

Xanthenediones derivatives have attracted considerable interests in recent times because they constitute a structural unit in a number of natural products1 and have been used as versatile synthons due to the inherent reactivity of the inbuilt pyran ring2. The conventional syntheses of xanthenediones were acid or base catalyzed condensation of appropriate active methylene carbonyl compounds with aldehydes3. However, many of these procedures involved longer reaction times,low yields and side reactions of aldehydes. In recent years, room temperature ionic liquids (RTILs) have been used as novel green reaction media4. Considering that InCl3 is an efficient Lewis acid catalyst used in promoting many organic reactions, especially in several condensation processes, we herein wish to report a very simple and green method for the preparation of poly-hydrogenated xanthenediones through InCl3·4H2O promoted cascade reaction of aldehydes and 5,5-dimethyl-l,3-cyclohexanedione in ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The preparative process presented here is operationally simple, environmentally benign and has the advantage of enhanced atom utilization. Furthermore, the solvent and the catalyst used can be recovered easily and reused efficiently.     

Inter- and intramolecular radical couplings of ene-ynes or halo-alkenes promoted by an InCl3/MeONa/Ph2SiH2 system

[reaction: see text] An effective generation of indium hydride (HInCl(2)) under nonacidic conditions is achieved by transmetalation between Ph(2)SiH(2) and InCl(2)OMe. The presented system achieves the titled coupling reactions in a radical manner. In particular, the nonacidic character enables the applications to acid-sensitive inter- and intramolecular ene-yne couplings.     

Novel 1,3-dipolar cycloaddition of diazocarbonyl compounds to alkynes catalyzed by InCl3 in water

The first intermolecular 1,3-dipolar cycloaddition of diazocarbonyl compounds with alkynes was developed by using an InCl(3) catalyzed cycloaddition in water. The reaction was found to proceed by a domino 1,3-dipolar cycloaddition-hydrogen (alkyl or aryl) migration.     

InCl3-catalyzed regio- and stereoselective thiolysis of alpha,beta-epoxycarboxylic acids in water

[reaction: see text] The thiolysis of alpha,beta-epoxycarboxylic acids 1a-e by thiols 2a,b is more efficient in water than in dichloromethane or SFC. At pH 9.0 phenylthiolate generally attacks the C-alpha carbon while at pH 4.0, and in the presence of InCl3 (10 mol %), the thiolysis is exclusively C-beta regioselective. In all cases, the processes are completely anti-diasteroselective, and the corresponding products 3, 4, and 5 have been isolated in good yields. Both water and catalysts have been recovered and reused.     

Concise total synthesis of the aporphine alkaloid 7,7''-bisdehydro-O-methylisopiline by an InCl3 mediated cycloisomerization reaction

A novel InCl3 mediated cycloisomerization reaction leading to 10-halophenanthrene derivatives constitutes the key step of the first total syntheses of O-methyldehydroisopiline 10 and 7,7'-bisdehydro-O-methylisopiline 11, two prototype members of the aporphine family of alkaloids.     

Kinetically Controlled Solid State Reactions in the System InCl/SnCl2

This paper reports on studies on the reaction of InCl with SnCl₂ to form ternary halides. The reaction route is investigated by x‐ray investigations at different temperatures. Depending on the modification of InCl as educt and on the temperature conditions the reaction follows different pathways which may include intermediate redox reactions of the type In⁺ + Sn²⁺ → In³⁺ + Sn⁰.     

A simple and effcient approach to one-pot synthesis of mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates catalyzed by InCl3简

An efficient and straightforward procedure has been developed for the synthesis of highly substituted mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via a one-pot, four-component domino reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of InCl3 （20 mol%） in MeOH at ambient temperature. The salient advantages of this method are mild reaction conditions, environmentally benign, high to excellent yields, shorter reaction times, easy operation and no column chromatographic separation.     

In/InCl(3)-Mediated cross-coupling reactions of methyl vinyl ketone with benzaldehyde in aqueous media

Various beta,gamma-unsaturated ketones were successfully prepared by cross-coupling reactions of methyl vinyl ketone (MVK) with benzaldehydes mediated by In/InCl(3) in aqueous media.     

Extensive theoretical studies on the low-lying electronic states of indium monochloride cation, InCl+

The global potential energy curves for the 14 low-lying doublet and quartet Lambda-S states of InCl+ are calculated at the scalar relativistic MR-CISD+Q (multireference configuration interaction with single and double excitations, and Davidson's correction) level of theory. Spin-orbit coupling is accounted for via the state interaction approach with the full Breit-Pauli Hamiltonian, which leads to 30 Omega states. The computed spectroscopic constants of nine bound Lambda-S states and 17 bound Omega states are in good agreement with the available experimental data. The transition dipole moments and Franck-Condon factors of selected transitions are also calculated, from which the corresponding radiative lifetimes are derived.     

New visible emission spectra of GaBr, GaCl and InCl. Prospects of new laser transitions

Broad emission spectra have been observed for the first time in the visible region at 4600, 5000 and 5750 Å and are assigned to the diatomic molecules GaBr, GaCl and InCl, respectively. No structure is seen on the low-frequency side, while on the high-frequency side, some undulatory fluctuation bands are observed. The electronic transition is identified as a transition from an upper bound singlet or a triplet electronic state to the lower C ¹Π state which is predissociated. These transitions hold the potential to be developed into an efficient excimer laser medium, similar to the laser action obtained in the rare gas halides.