Aluminum

Saitō, Susumu

doi:10.1016/b0-08-045047-4/00113-8

Cited by 5 publications

(4 citation statements)

References 320 publications

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“…Me 3 Al, Et 3 Al, and i -Bu 3 Al are the most important industrial organoaluminum reagents. However, the reactions of organic n -butyl aluminum compounds are rare due to their instability and difficulty in synthesis. , …”

Section: Introductionmentioning

confidence: 84%

Alkylaluminum Complexes as Precatalysts in Hydroboration of Nitriles and Carbodiimides

Ding

Liu

et al. 2019

Organometallics

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The metathesis reaction of aluminum(III) dihydride LAlH 2 (1) (L = (ArNCMe) 2 CH, Ar = 2,6-i-Pr 2 C 6 H 4 ) with n-BuLi and n-Bu 2 Mg, respectively, resulted in di-n-butyl aluminum complex LAl(n-Bu) 2 (2). Meanwhile 1 reacted with MeLi producing dimethyl aluminum LAlMe 2 (3). Complexes 2 and 3 were characterized by NMR and elemental analysis, and 2 was additionally studied by single-crystal X-ray diffraction. The reported synthesis allows for access of dialkylaluminum complexes from aluminum-(III) dihydride compound (1) with excellent yields. The chemoselective double hydroboration of nitriles or single hydroboration of carbodiimides was studied with pinacolborane (HBpin) using LAl(n-Bu) 2 (2) as the precatalyst to afford bis(boryl)amines (4a−4m) and N-borylamines (6a− 6d) under solvent-free and mild conditions (60 °C). The records show that the catalytic reactions proceed in quantitative yields and short time. Moreover, nearly quantitative yield of di(boryl)(silyl)amine ( 5) was obtained, when cyanobenzene was reacted with equal amounts of HBpin and phenylsilane in the presence of precatalsyt 2. A comparison of the previously reported hydroboration reactions with nitriles in the literature and our results in the presence of the precatalyst LAl(n-Bu) 2 show convincingly the better results of short reaction time, mild reaction conditions, and quantitative yields.

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Section: Introductionmentioning

confidence: 84%

Alkylaluminum Complexes as Precatalysts in Hydroboration of Nitriles and Carbodiimides

Ding

Liu

et al. 2019

Organometallics

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“…Surprisingly, general preparations of arylaluminum reagents are rare. 2 The most important syntheses of arylaluminum compounds are directed aluminations, 3,4 transmetalation reactions. 5 Most transmetalations from highly reactive organolithium reagents have to be performed at low temperature.…”

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confidence: 99%

New Preparation and Reactions of Arylaluminum Reagents Using Barbier Conditions

Gao¹,

Knöchel²

2009

Synlett

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P r e p a r a t i o n a n d R e a c t i o n s o f A r y l a l u m i n u m R e a g e n t s Abstract: The reaction of various aryl bromides with magnesium turnings, LiCl and R 2 AlCl (R = Et, i-Bu) provides at room temperature arylaluminum reagents in high yields. These organometallic species undergo readily 1,4-additions, acylations, allylations, and Pd-catalyzed cross-couplings with various aryl iodides and bromides.The preparation of main-group organometallics for applications in organic synthesis is one of the most active research areas in organic chemistry since these organometallics readily form new carbon-carbon bonds. Previously unrecognized high chemoselectivity of zinc and magnesium reagents led to an increased research activity in this field. 1 The preparation of organoaluminum derivatives is of special interest due to the potentially broad functionalgroup tolerance of organoalanes, the low cost of aluminum reagents, and their low toxicity. Surprisingly, general preparations of arylaluminum reagents are rare. 2 The most important syntheses of arylaluminum compounds are directed aluminations, 3,4 transmetalation reactions. 5 Most transmetalations from highly reactive organolithium reagents have to be performed at low temperature. 5 Recently, we have found that the insertion of various metals (Zn, 6 In, 7 Mg 8 ) is dramatically accelerated by the addition of LiCl. Also, the use of Barbier reaction conditions allows to generate sensitive organozinc reagents via reactive intermediate magnesium reagents which are trapped in situ with ZnCl 2 . 8 Using a similar approach, we wish to report herein a new preparation method of arylaluminum reagents of type 1 (Scheme 1) which proceeds at room temperature via an in situ generated organomagnesium species of type 2 obtained by the reaction of aryl bromides 3 with magnesium turnings in the presence of LiCl and a dialkylaluminum chloride (R 2 AlCl; 4a: R = Et; 4b: R = iBu). Scheme 1Thus, the treatment of 4-bromoanisole (1.0 equiv) with magnesium turnings (2.5 equiv) activated with DIBAL-H (1%), 9 LiCl (1.25 equiv), and Et 2 AlCl (1.0 M solution in hexane, 1.1 equiv) at 25°C provides the corresponding arylaluminum reagent 1a within 3 hours as indicated by GC analysis of hydrolyzed reaction aliquots. The crude arylaluminum reagent is cannulated to a solution of CuCN·2LiCl (0.1 equiv) 9 at -10°C followed by cyclohex-2-enone (0.6 equiv) and TMSCl (1.1 equiv). 5b After acidic workup, the 3-arylated cyclohexanone 4a is isolated in 72% yield (entry 1 of Table 1). This Michael addition was extended to arylaluminum reagents bearing a chlorine substituent (1b,c, entries 2 and 3) leading to the 3-substituted cyclohexanones 4b,c in 71-77% yield. The ortho-tolylaluminum species 1d also reacts smoothly with cyclohex-2-enone affording the 1,4-adduct 4d in 76% yield (entry 4). Finally, amino-substituted arylaluminum species such as 1e can be readily prepared with our method providing after the addition to ethyl acrylate the b-arylated ester 4e in 66% yield (entry 5). The competitive tr...

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“…Alkyl aluminum-type compounds, such as trimethylaluminum, represent an approximation to the role of aluminum in organometallic chemistry and have been extensively studied, expanding their scope in catalytic applications and even in materials science 57 . These compounds, like Al (III) by itself, have a high oxophilicity, which leads to the disadvantage of being highly unstable in air and humidity; they exhibit pyrophoricity, that is, they ignite at room temperature in the presence of oxygen, in addition to the fact that they react violently with water.…”

Section: General Aspects Of Aluminum Complexesmentioning

confidence: 99%

“…The properties and characteristics related to the reactivity of aluminum (III) reagents generally derive from the high Lewis acidity of the organoaluminum compounds. This property allows the formation of complexes through covalent or coordination bonds; the latter originated when the acidic species Al−R reacts with a Lewis base, with a pair of electrons available to occupy the empty orbitals around the aluminum atom [56][57][58] .…”

Section: General Aspects Of Aluminum Complexesmentioning

confidence: 99%

Sn, Ge and Al compounds stabilized by bis-amidine, bis-sulfonimidamide, and Schiff base ligands: synthesis and reactivity

Riveros¹

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Teniendo en cuenta los problemas actuales relacionados con el medio ambientales que afectan a nuestro planeta, como el efecto invernadero, el calentamiento global y la acumulación de residuos plásticos, producidos por la emisión de gases como CO2 a la atmosfera y el uso indiscriminado de plásticos, es necesario estrategias para disminuir estos problemas, y una de estas es desarrollar sistemas catalíticos mediante la síntesis de nuevos compuestos, para así usar los contaminantes como CO2, CO, CH4, etc. para obtener nuevos compuestos con valor agregado. Por lo tanto, en este proyecto de tesis se sintetizaron germilenos y estanilenos con ligandos bisamidinas con un puente rígido de naftaleno. Estos sistemas fueron usados como catalizadores en reacciones de polimerización de esteres cíclicos, pero no presentaron la reactividad deseada. Sin embargo, para entender y saber las propiedades de estos nuevos compuestos y la reactividad que poseen es que de igual manera se probaron frente a reacciones del tipo oxidación, adición oxidativa, coordinación y transmetalación. Por otra parte, fue posible sintetizar nuevos complejos bis-aluminio con ligando bis-amidinas con un puente rígido de naftaleno, los cuales fueron testeado como catalizador para la obtención de carbonatos cíclicos a partir de epóxidos y CO2, que presentaron de moderada a excelente conversión. Asimismo, fue posible obtener un complejo de aluminio usando el mismo ligando bis-amidina, pero incorporando yoduros en su estructura para utilizarlo como un catalizador de un componente, pero desafortunadamente no presento actividad catalítica. Se sintetizo un ligando base de Schiff derivado de ferroceno, con su respectivo complejo de aluminio, el cual presentó baja actividad catalítica para la obtención de carbonatos cíclicos a partir de epóxidos y CO2. En cuanto a los ligandos bis-sulfonimidamida que contengan un puente en su estructura, a pesar de las múltiples pruebas, no fue posible obtenerlos.

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Aluminum

Cited by 5 publications

References 320 publications

Alkylaluminum Complexes as Precatalysts in Hydroboration of Nitriles and Carbodiimides

Alkylaluminum Complexes as Precatalysts in Hydroboration of Nitriles and Carbodiimides

New Preparation and Reactions of Arylaluminum Reagents Using Barbier Conditions

Sn, Ge and Al compounds stabilized by bis-amidine, bis-sulfonimidamide, and Schiff base ligands: synthesis and reactivity

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