Aluminum Reagents Research Articles

ChemInform Abstract: Asymmetric Addition of Pyridyl Aluminum Reagents to Aldehydes Catalyzed by a Titanium(IV) Catalytic System of (R)‐H8‐BINOLate.

AbstractA series of optically active pyridyl methanols is available with the title reaction.

Asymmetric Addition of Pyridyl Aluminum Reagents to Aldehydes Catalyzed by a Titanium(IV) Catalytic System of (R)-H8-BINOLate.

The asymmetric addition of pyridyl aluminum reagents to aldehydes has been successfully developed by employing a titanium(IV) catalytic system of (R)-H8-BINOLate, which affords a series of valuable optically active diarylmethanols containing various pyridyl groups in high yields with excellent enantioselectivities of up to 98% ee.

Iron-Catalyzed Directed C(sp(2))-H and C(sp(3))-H Functionalization with Trimethylaluminum.

Conversion of a C(sp(2))-H or C(sp(3))-H bond to the corresponding C-Me bond can be achieved by using AlMe3 or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.

ChemInform Abstract: α‐Heteroarylation of Ketones via the Umpolung Reaction of N‐Alkoxyenamine.

A new method has been developed for the umpolung α-heteroarylation of ketones via an N-alkoxyenamine. The treatment of ketones with tris(heteroaryl)aluminum reagents in the presence of isoxazolidine gave the corresponding α-heteroarylated ketones in moderate to good yields.

An automated method for monitoring aluminum in water samples based on a sequential injection platform

The simple colour reaction between aluminum(iii) and aluminon reagent was transferred to an automated sequential injection system.

Regio- and stereoselective multisubstituted olefin synthesis via hydro/carboalumination of alkynes and subsequent iron-catalysed cross-coupling reaction with alkyl halides

A new synthetic route towards multisubstituted olefins was developed based on the direct cross coupling of alkenyl aluminium reagents, prepared by hydro- and carboalumination, with alkyl halides in the presence of an iron catalyst.

Activation of [CrCl3{R-SN(H)S-R}] Catalysts for Selective Trimerization of Ethene: A Freeze-Quench Cr K-Edge XAFS Study

Homogeneous chromium catalysts for the selective conversion of ethene to hex-1-ene are formed from Cr(III) reagents, aminothioether ligands of the type HN(CH2CH2SR)2, and aluminum reagents. In this study, the early activation steps are investigated by EPR, UV–visible, and Cr K-edge XAFS spectroscopy; rapid stopped-flow mixing and a freeze-quench allows good quality EXAFS analysis of a species formed in ∼1 s of reaction. This is shown to involve reduction to Cr(II) and deprotonation of a NH group of the auxiliary ligand. This 4-coordinate metal center may act as precursor for the coordination of ethene and subsequent selective oligomerization.

Simple Homopolymer-incarcerated Gold Nanoclusters Prepared by Self-assembled Encapsulation with Aluminum Reagents as Crosslinkers: Catalysts for Aerobic Oxidation Reactions

Abstract Simple homopolymer-incarcerated gold nanocluster catalysts were developed using a self-assembled encapsulation strategy. In this method, Red-Al® acting as a reductant also played the role of an inter-crosslinker via the formation of tetraalkoxyaluminate with the hydroxy groups in a homopolymer. Gold nanoclusters could be immobilized at high loadings without aggregation, and high catalytic activities were observed in several aerobic oxidation reactions.

ChemInform Abstract: Highly Diastereoselective Addition of Alkoxyethynyl Aluminum Reagents to N‐tert‐Butylsulfinyl Aldimines.

AbstractThe addition of in situ generated alkoxyethynyl aluminum reagents (II) to sulfinylimines (III) affords alkoxypropargylamines (IV) in high yields and with significant higher diastereoselectivities compared to the reaction of the corresponding lithio acetylides.

ChemInform Abstract: Regiocontrolled Ring Opening of Monoprotected 2,3‐Epoxy‐1,4‐diols by Using Alkynyl Aluminum Reagents: Synthesis of Differentially Monoprotected Alkynyl Triol Derivatives.

AbstractThe reaction of epoxy‐alcohols of type (I) and (V) with aluminum alkynes is studied.

ChemInform Abstract: Highly Diastereoselective Preparation of Aldol Products Using New Functionalized Allylic Aluminum Reagents.

AbstractThe title aluminum reagents are prepared from the corresponding allylic chlorides and aluminum powder as a solution in THF which is directly used in the reactions with the aromatic carbonyl compounds.

ChemInform Abstract: Synthesis of Heteroaryl Compounds Through Cross‐Coupling Reaction of Aryl Bromides or Benzyl Halides with Thienyl and Pyridyl Aluminum Reagents.

AbstractAn efficient method for synthesis of useful biaryl building blocks containing thienyl or pyridyl moieties is provided through cross‐coupling reactions of freshly prepared heteroaryl aluminum reagents with aryl bromides or benzyl halides.

Highly Diastereoselective Preparation of Aldol Products Using New Functionalized Allylic Aluminum Reagents

Chloro-substituted triethylsilyl enol ethers derived from cyclohexanone and related ketones are converted with aluminum powder in the presence of indium trichloride to functionalized allylic aluminum reagents which represent a new type of synthetic equivalent of metal enolates. These allylic organometallics undergo highly diastereoselective additions to aldehydes and methyl aryl ketones, giving aldol products with a β-quaternary center.

α-Heteroarylation of ketones via the umpolung reaction of N-alkoxyenamine.

A new method has been developed for the umpolung α-heteroarylation of ketones via an N-alkoxyenamine. The treatment of ketones with tris(heteroaryl)aluminum reagents in the presence of isoxazolidine gave the corresponding α-heteroarylated ketones in moderate to good yields.

Highly diastereoselective addition of alkoxyethynyl aluminium reagents to N-tert-butylsulfinyl aldimines

The addition of dimethylaluminium alkoxyacetylides to Ellman's sulfinylimines is described. The reaction proceeds with excellent diastereoselectivity and high yield to produce oxygenated propargylamines in one step starting from simple dichloroenol ethers.

The synthesis and application of novel Ni(II) N-alkyl dipyridylaldiminato complexes as selective ethylene oligomerisation catalysts.

A series of N-alkyl 2,2'-dipyridylamine ligands of general formula (2-C5H3NR)2NR', (a): R = H, R' = Me; (b): R = H, R' = benzyl; (c): R = H, R' = methylcyclohexyl; (d): R = H, R' = neopentyl; (e): R = Me, R' = Me) were prepared by a modified method involving base-mediated N-alkylation with the respective alkyl halide. Reaction of the ligands, a-e, with NiCl2(DME) allowed for the isolation of μ-Cl Ni(ii) complexes: [Ni(μ-Cl){a}Cl]2 (1a); [Ni(μ-Cl){b}Cl]2 (1b); [Ni(μ-Cl){c}Cl]2 (1c); [Ni(μ-Cl){d}Cl]2 (1d) and [Ni(μ-Cl){e}Cl]2 (1e). The complexes were characterised by FT-IR spectroscopy, magnetic susceptibility measurements, mass spectrometry, elemental analyses and in the case of 1a, SCD analysis. In the case of complex 1e, an acid-mediated hydrolysis process was identified. The product of hydrolysis, the protonated ligand and a tetrachloronickelate salt (1e-A), was characterised by SCD analysis. Activation of 1a-1e with alkyl aluminium reagents generated highly active catalysts for the oligomerisation of ethylene, with activities of up to 864 kgoligomers molNi(-1) h(-1) and high selectivity toward the formation of butenes. In general, trans 2-butene was observed as the major isomer, with the exception of 1e. In the case of 1e, the selectivity for 1-butene was 98%, thereby demonstrating the significant effect that the introduction of a low degree of steric pressure in the coordination sphere of the catalyst has on selectivity.

Synthesis of tertiary propargylic phosphonates by addition of trialkynylaluminum reagents to acyl phosphonates and investigation of their antimicrobial activities

A series of propargylic alcohols containing phosphonates was synthesized by addition reactions of tris-(propynyl) and tris-(phenylethynyl)aluminum reagents to acyl phosphonates in good yields. Aromatic moieties of the acyl phosphonates with electron-withdrawing groups generally resulted in better isolated chemical yield. Selected propargylic phosphonates were tested for antimicrobial activities. Compounds 3a and 3h showed noticeable antifungal activity, especially against molds.

Synthesis of Heteroaryl Compounds through Cross-Coupling Reaction of Aryl Bromides or Benzyl Halides with Thienyl and Pyridyl Aluminum Reagents

An efficient method for synthesis of useful biaryl building blocks containing 2-thienyl, 3-thienyl, 2-pyridyl, and 3-pyridyl moieties was provided through cross-coupling reactions of aryl bromides or benzyl halides with heteroaryl aluminum reagents in the presence of Pd(OAc)2 and (o-tolyl)3P. The coupling reaction also worked efficiently with heteroaryl bromides affording series of heterobiaryl compounds. The reaction of phenylbromide with in situ prepared 3-pyridyl aluminum was demonstrated to afford the product 8a in high yield. Additionally, the catalytic system was also suited well for the coupling reaction of benzyl halides with pyridyl aluminum reagents to afford series of pyridyl-arylmethane.

Regiocontrolled ring opening of monoprotected 2,3-epoxy-1,4-diols using alkynyl aluminum reagents. Synthesis of differentially monoprotected alkynyl triol derivatives.

The regioselectivity of the epoxide ring opening reaction of cis and trans TIPS-monoprotected 2,3-epoxy-1,4-diols with diethylalkynyl aluminum reagents was studied. Alane and alanate conditions in toluene or dichloromethane were explored. The alkynyl attack at the C2 epoxide carbon was favored for both, the alane and alanate conditions in toluene, while in dichloromethane the C3 attack was preferred. The best regioselectivities were obtained using the alanate conditions in toluene. This methodology provides access to differentially monoprotected alkynyl triols with high diastereoselectivity. These compounds are useful building bocks for polypropionate synthesis and are precursors for the introduction of the hydroxymethyl moiety found in some polyketide systems.

Synthesis and characterization of ordered mesoporous aluminosilicate molecular sieve from natural halloysite

Currently, opening up the possibility of low-cost mineral for preparing ordered mesoporous materials is of significant importance. In the present work, hexagonally ordered mesoporous aluminosilicate molecular sieve was hydrothermally synthesized from natural halloysite without addition of silica or aluminum reagents. The mesoporous structure of the synthesized materials was confirmed by small angle X-ray diffraction and nitrogen sorption analysis. Scanning electron microscope and transmission electron microscope observations indicated that highly ordered two-dimensional hexagonal mesoporous structure was obtained. Wide angle X-ray diffraction and Fourier transform infrared spectroscopy were also used to examine the variations of chemical structures. The surface area of the prepared material after being calcined at 550°C was 524.6m2/g and the pore volume was 0.87cm3/g. 27Al solid state magic angle spinning nuclear magnetic resonance spectrum showed that all of aluminum species were tetrahedrally coordinated into the framework of the mesoporous material. A possible mechanism for the formation of aluminosilicate molecular sieves from natural halloysite was also discussed accordingly.