Diisobutylaluminum Hydride Research Articles

Rational design and synthesis of aldehyde-functionalized mesoporous SBA-15 for high-performance ammonia sensor

Herein, we report novel ammonia gas sensor materials having aldehyde functional groups grafted onto the pore surface of highly ordered mesoporous materials SBA-15. The functional SBA-15 was synthesized via co-condensation of tetraethyl orthosilicate and formylsilanetriol using an amphiphilic block copolymer P123 as a structure-directing agent, in which formylsilanetriol was first synthesized through the reduction of 2-cyanoethyltriethoxysilane in the presence of diisobutylaluminium hydride. Structural and textural characterizations by x-ray diffraction, transmission electron microscopy and N2 adsorption–desorption porosimetry were conducted and the results show the materials having well-defined mesoporous long-range ordering with pore size of 6.2nm. Furthermore, FT-IR and solid-state magic angle spinning nuclear magnetic resonance spectroscopy studies proved covalent anchoring of the aldehyde functional group onto the pore walls of SBA-15. The results indicated that the materials successfully kept their mesoporous nature after grafting of the aldehyde groups. Gas-sensing tests were investigated by coating the aldehyde-functionalized SBA-15 onto quartz crystal microbalance transducers. The results reveal that the sensors can be as promising candidates as ammonia detectors with desirable sensing behaviors, including high sensitivity (the frequency shift was 22Hz at 1ppm and the QCM sensors were exposed to nitrogen stream until a stable baseline (±2Hzmin−1)), fast response (response time within 11s, recovery time within 13s) and good reversibility.

Diisobutylaluminum borohydride: An efficient reagent for the reduction of tertiary amides to the corresponding amines under ambient conditions

A synthetically simple mixed metal hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], is easily generated from a 1:1 mixture of borane-dimethylsulfide (BMS) and diisobutylaluminum hydride (DIBAL). The reduction of tertiary amides using (iBu)2AlBH4 is complete within five minutes under ambient conditions and the product tertiary amines were isolated in 70–99% yields by a simple acid-base extraction. This new methodology, reported herein, works well for reduction of tertiary aliphatic and aromatic amides as well as lactams to the corresponding amines and product isolation and purification does not require column chromatography.

Total Synthesis of (±)-Ramariolides C and D

Ramariolides A–D (1–4) were isolated from the coral mushroom Ramaria cystidiophora, out of which 1 showed in vitro antimicrobial activity. The structural features of 1–4 are attractive synthetic targets. Here, we report the total synthesis of ramariolides C (3) and D (4). The vinylogous Mukaiyama aldol reaction was employed to construct the carbon skeletons of 3 and 4. The key precursors for the reaction were α-hydroxyaldehydes, which were prepared from cyanohydrins via reduction with diisobutylaluminum hydride (DIBAL). Successive acetylation of the aldol adducts and an elimination reaction of the resulting acetates yielded 3 and 4 upon treatment with tetra-n-butylammonium fluoride (TBAF) and acetic acid.

First total synthesis of quiquesetinerviusin A

The first total synthesis of the dihydrobenzofuran neolignan quiquesetinerviusin A and its related structure have been described. Phenolic coupling is the key step to constructing the dihydrobenzofuran skeleton with vanillin as the raw material. The hydroxyl group was protected with dihydropyran (DHP) and the ester group was reduced with diisobutylaluminium hydride (DIBAL-H) in order to obtain the crucial intermediate diol, which was then condensed with an acid ligand to give the desired compounds following removal of the protecting groups.

Convenient synthesis of trans-3-amino-1-benzylpiperidin-4-ols using regiospecific cleavage of 1-benzyl-3,4-epoxypiperidine with diisobutylaluminum amides (DIBAL-NR1R2)

The report presents a first example of a regio- and stereospecific Lewis acid-catalyzed aminolysis of 1-benzyl-3,4-epoxypiperidine leading to trans-3-amino-1-benzylpiperidin-4-ols, in contrast with other Lewis acid-catalyzed reactions leading to trans-4-amino-1-benzylpiperidin-3-ols. The reaction is performed at room temperature using the reagents prepared by interaction of a hard Lewis acid – diisobutylaluminum hydride (DIBAL-H) with primary and secondary amines. The obtained products are potential intermediates on the way to stereochemical analogues of the antitumor piperidine alkaloid pseudodistomin D.

Silole Synthesis Promoted by DIBAL-H

Silole Synthesis Promoted by DIBAL-H

Diisobutylaluminum hydride-promoted cyclization of silylated 1,3-dien-5-ynes: Application to total synthesis of a 20-norabietane derivative

The diisobutylaluminum hydride (DIBAL-H)-promoted benzocyclization, recently developed by this group, was adopted for the synthesis of a natural product containing a 9,10-dihydrophenanthrene skeleton to demonstrate its synthetic utility. One of the extracts from the roots of Salvia hydrangea DC. ex Bentham (Lamiaceae), a 20-norabietane derivative, was selected as the target molecule. The key step forming the 9,10-dihydrophenanthrene skeleton was achieved by the DIBAL-H-promoted cyclization of a silylated 1,3-dien-5-yne easily accessible from a substituted α-tetralone.

Diisobutylaluminum Hydride Promoted Cyclization of 1-Hydrosilyl-4-silyl-1,3-enynes to Polysubstituted Siloles.

An efficient method for preparing unsymmetrically multisubstituted siloles is described. The reaction of 1-hydrosilyl-4-silyl-1,3-enynes with diisobutylaluminum hydride (DIBAL-H) gave multisubstituted siloles in good to high yields. This method could be applied to the synthesis of benzosiloles using 2-hydrosilyl-1-(silylethynyl)benzenes as substrates. The silole formation was also promoted even by a substoichiometric amount of DIBAL-H. The reaction provides a straightforward method to prepare siloles and benzosiloles.

ChemInform Abstract: Selective Mono‐Reduction of Pyrrole‐2,5‐ and ‐2,4‐dicarboxylates.

AbstractThe title compounds are rapidly and selectively reduced to the corresponding mono‐alcohols using diisobutylaluminum hydride as reductant.

ChemInform Abstract: Diisobutylaluminum Hydride‐Promoted Cyclization of Benzyl and Phenylsilyl Ethers Bearing a 2‐(Trimethylsilyl)ethynyl Group: Syntheses of Indenes and Benzosiloles.

Abstract The reaction of o -[2-(trimethylsilyl)ethynyl]benzyl methyl ethers with diisobutylaluminum hydride (DIBAL-H) gave 2-(trimethylsilyl)indenes in good yields. This cyclization proceeds by regio- and stereoselective hydroalumination of the alkyne moiety followed by intramolecular nucleophilic substitution. o -[2-(Trimethylsilyl)ethynyl]phenylsilyl methyl ethers also underwent the DIBAL-H promoted-cyclization to be converted into 2-(trimethylsilyl)benzosiloles in good yields. This approach provides straightforward and efficient way to construct benzosiloles from readily available organosilanes.

Single-Site Tetracoordinated Aluminum Hydride Supported on Mesoporous Silica. From Dream to Reality!

The reaction of mesoporous silica (SBA15) dehydroxylated at 700 °C with diisobutylaluminum hydride, i-Bu2AlH, gives after thermal treatment a single-site tetrahedral aluminum hydride with high selectivity. The starting aluminum isobutyl and the final aluminum hydride have been fully characterized by FT-IR, advanced SS NMR spectroscopy (1H, 13C, multiple quanta (MQ) 2D 1H–1H, and 27Al), and elemental analysis, while DFT calculations provide a rationalization of the occurring reactivity. Trimeric i-Bu2AlH reacts selectively with surface silanols without affecting the siloxane bridges. Its analogous hydride catalyzes ethylene polymerization. Indeed, catalytic tests show that this single aluminum hydride site is active in the production of a high-density polyethylene (HDPE).

Facile, Economic and Size-Tunable Synthesis of Metal Arsenide Nanocrystals

Synthesis of colloidal nanocrystals (NC) of important arsenide nanomaterials (e.g., InAs, Cd3As2) has been limited by the lack of convenient arsenic precursors. Here we address this constraint by identifying a convenient and commercially available As precursor, tris-dimethylaminoarsine (As(NMe2)3), which can be used to prepare high quality InAs NCs with controlled size distributions. Our approach employs a reaction between InCl3 and As(NMe2)3 using diisobutylaluminum hydride (DIBAL-H) to convert As(NMe2)3 in situ into reactive intermediates AsHx(NMe2)3–x, where x = 1,2,3. NC size can be varied by changing DIBAL-H concentration and growth temperature, with colloidal solutions of InAs showing size dependent absorption and emission features tunable across wavelengths of 750 to 1450 nm. We also show that this approach works well for the colloidal synthesis of Cd3As2 NCs. By circumventing the preparation of notoriously unstable and dangerous arsenic precursors (e.g., AsH3 and As(SiMe3)3), this work improves th...

ChemInform Abstract: Controlled Reduction of Tertiary Amides to the Corresponding Alcohols, Aldehydes, or Amines Using Dialkylboranes and Aminoborohydride Reagents.

AbstractThe efficient reduction of various N,N‐dialkyl substituted aryl, alkenyl or alkyl amides, Weinreb‐amides and lactams is examined, and depending on the boron‐containing reducing agent used, the corresponding alcohols, aldehydes, amines or N‐methoxy‐N‐methylamines are obtained exclusively.

Regioselective Intermolecular [2 + 2]-Cycloaddition of α-Iodo-Unsaturated Ketones Promoted by Diisobutylaluminum Hydride.

The development of intermolecular [2 + 2]-cycloaddition of α-iodo-unsaturated ketones in the presence of diisobutylaluminum hydride (Dibal-H) is reported to produce various trispirocyclic derivatives containing a cyclobutane ring. This sequential lactonization/[2 + 2]-cycloaddition proceeds in high regioselectivity under mild conditions.

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines.

The synthesis of novel tetrahydroquinolines (THQ) and dihydroquinolines (DHQ) are reported using three practical, scalable synthetic approaches to access highly lipophilic analogues bearing a 6-iodo substituent, each with a different means of cyclisation. A versatile and stable quinolin-2-one intermediate was identified, which could be reduced to the corresponding THQ with borane reagents, or to the DHQ with diisobutylaluminium hydride via a novel elimination that is more favourable at higher temperatures. Coupling these strongly electron-donating scaffolds to electron-accepting moieties caused the resulting structures to exhibit strong fluorescence.

ChemInform Abstract: Diisobutylaluminum Hydride‐Promoted Cyclization of O‐(Trimethylsilylethynyl)styrenes to Substituted Naphthalenes.

Abstract The reaction of α,β-disubstituted ( E )- o -(trimethylsilylethynyl)styrenes with a substoichiometric amount of diisobutylaluminum hydride at 100 °C gave 1,2,3-trisubstituted naphthalenes. This benzocyclization is initiated by regioselective hydroalumination of the alkyne moiety, and the resultant alkenylaluminums lead to naphthalenes through intramolecular carboalumination, skeletal rearrangement, and dehydroalumination steps. The silylated products could be efficiently transformed into iodinated polycyclic aromatic hydrocarbons.

Diisobutylaluminum hydride-promoted cyclization of benzyl and phenylsilyl ethers bearing a 2-(trimethylsilyl)ethynyl group: syntheses of indenes and benzosiloles

The reaction of o-[2-(trimethylsilyl)ethynyl]benzyl methyl ethers with diisobutylaluminum hydride (DIBAL-H) gave 2-(trimethylsilyl)indenes in good yields. This cyclization proceeds by regio- and stereoselective hydroalumination of the alkyne moiety followed by intramolecular nucleophilic substitution. o-[2-(Trimethylsilyl)ethynyl]phenylsilyl methyl ethers also underwent the DIBAL-H promoted-cyclization to be converted into 2-(trimethylsilyl)benzosiloles in good yields. This approach provides straightforward and efficient way to construct benzosiloles from readily available organosilanes.

An unexpected effect of acetal stereochemistry on the course of its reductive cleavage

During the course of studies toward the synthesis of the ‘upenamide BC spirocycle a surprising effect of acetal stereochemistry on the course of its reductive cleavage was observed. Reduction of alpha acetal 6a with diisobutylaluminum hydride led to PMB ether 10, while the corresponding beta acetal 6b was resistant to reduction with diisobutylaluminum hydride, but on treatment with sodium cyanoborohydride–trimethylsilyl chloride afforded PMB ether 8.

Controlled Reduction of Tertiary Amides to the Corresponding Alcohols, Aldehydes, or Amines Using Dialkylboranes and Aminoborohydride Reagents.

Dialkylboranes and aminoborohydrides are mild, selective reducing agents complementary to the commonly utilized amide reducing agents, such as lithium aluminum hydride (LiAlH4) and diisobutylaluminum hydride (DIBAL) reagents. Tertiary amides were reduced using 1 or 2 equiv of various dialkylboranes. The reduction of tertiary amides required 2 equiv of 9-borabicyclo[3.3.1]nonane (9-BBN) for complete reduction to give the corresponding tertiary amines. One equivalent of sterically hindered disiamylborane reacts with tertiary amides to afford the corresponding aldehydes. Aminoborohydrides are powerful and selective reducing agents for the reduction of tertiary amides. Lithium dimethylaminoborohydride and lithium diisopropylaminoborohydride are prepared from n-butyllithium and the corresponding amine-borane. Chloromagnesium dimethylaminoborohydride (ClMg(+)[H3B-NMe2](-), MgAB) is prepared by the reaction of dimethylamine-borane with methylmagnesium chloride. Solutions of aminoborohydride reduce aliphatic, aromatic, and heteroaromatic tertiary amides to give the corresponding alcohol, amine, or aldehyde depending on the steric requirement of the tertiary amide and the aminoborohydride used.

Synthesis of N,N,O-Trisubstituted Hydroxylamines by Stepwise Reduction and Substitution of O-Acyl N,N-Disubstituted Hydroxylamines.

Diverse N,N,O-trisubstituted hydroxylamines, an under-represented group in compound collections, are readily prepared by partial reduction of N-acyloxy secondary amines with diisobutylaluminum hydride followed by acetylation and reduction of the so-formed O-acyl-N,N-disubstituted hydroxylamines with triethylsilane and boron trifluoride etherate. Use of carbon nucleophiles in the last step, including allyltributylstannane, silyl enol ethers, and 2-methylfuran, gives N,N,O-trisubstituted hydroxylamines with branching α- to the O-substituent. N,N-Disubstiuted hydroxylamines are conveniently prepared by reaction of secondary amines with dibenzoyl peroxide followed by diisobutylaluminum hydride reduction.