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Complex metal hydrides are one of the most effective hydrogen storage materials due to their unique property to absorb and desorb hydrogen with the hydrogen storage capacity of about 5-7 wt%. In this study, lithium aluminium hydride (LiAlH4) was coated on glass substrate using dip coating method. The coating conditions investigated were LiAlH4 concentrations of 6 g/l, 10 g/l and 20 g/l and post-annealing time from 0 to 60 min. Phase and grain size of the deposited LiAlH4 were analyzed using X-ray powder diffraction (XRD). Scanning electron microscope (SEM) was used for surface morphology analysis. The hydrogen storage capacity of the deposited thin films was analyzed using thermogravimetric analysis (TGA). The experimental results revealed that the phase of the deposited LiAlH4 thin films on glass substrate were mixed with lithium aluminium hydroxide hydrate (LiAl2(OH)7·2H2O) and lithium hexahydroaluminate (Li3AlH6). The intensity of the LiAl2(OH)7·2H2O and LiAlH4 peaks tends to decrease with increasing LiAlH4 concentration and post-annealing time while the intensity of the Li3AlH6 peaks increased with increasing LiAlH4 concentration and post-annealing time. The grain size was decreased with increasing LiAlH4 concentration and post-annealing time. The smaller grain size the better the hydrogen storage capacity. The hydrogen storage capacity of the deposited LiAlH4 thin film was increased from 0.124 wt % using LiAlH4 concentration of 6 g/l without post-annealing to 1.675 wt % using LiAlH4 concentration of 20 g/l with 60 min post-annealing time.

3D printing of carbon-based nanocomposites, which combine the electrical properties of carbon additives with the benefits of thermoplastics, has emerged as a promising route towards rapid and low-cost manufacturing of customised-shaped electronic devices with minimised waste. However, their poor electrical activity in their pristine state makes activation post-treatments mandatory to reduce the amount of insulating polymer. These post-treatments typically involve the use of toxic organic solvents or costly thermal annealing methods. Herein, a simple eco-friendly wet-chemical post-treatment is presented for the quick and general activation of carbon-based 3D printed electronic devices by employing reducing agents like ascorbic acid or sodium borohydride. We tested a range of reducing agents, such as sodium borohydride, lithium aluminium hydride, hydrazine and ascorbic acid, as well as a model oxidising agent like hydrogen peroxide. We found that ascorbic acid and sodium borohydride are the most effective chemicals to achieve electrically active devices while preserving the shape and structure of the 3D printed carbon objects. Thus, this work allows the development of advanced carbon-based 3D printed electrodes by employing an eco-friendly activation approach.

Despite the application of lithium aluminium hydride (LiAlH4) being hindered by its sluggish desorption kinetics and unfavourable reversibility, LiAlH4 has received special attention as a promising solid-state hydrogen storage material due to its hydrogen storage capacity (10.5 wt.%). In this work, investigated for the first time was the effect of the nanosized cobalt titanate (CoTiO3) which was synthesised via a solid-state method on the desorption behaviour of LiAlH4. Superior desorption behaviour of LiAlH4 was attained with the presence of a CoTiO3 additive. By means of the addition of 5, 10, 15 and 20 wt.% of CoTiO3, the initial desorption temperature of LiAlH4 for the first stage was reduced to around 115–120 °C and the second desorption stage was reduced to around 144–150 °C, much lower than for undoped LiAlH4. The LiAlH4-CoTiO3 sample also presents outstanding desorption kinetics behaviour, desorbing hydrogen 30–35 times faster than undoped LiAlH4. The LiAlH4-CoTiO3 sample could desorb 3.0–3.5 wt.% H2 in 30 min, while the commercial and milled LiAlH4 desorbs

The addition of a catalyst and ball milling process was found to be one of the efficient method to reduce the decomposition temperature and improve the desorption kinetics of lithium aluminium hydride (LiAlH4). In this paper, a transition metal oxide, LaFeO3 was used as a catalyst. Decomposition temperature of the 10 wt% of LaFeO3-doped LiAlH4 system was found to be lowered from 143 °C to 103 °C (first step) and from 175 °C to 153 °C (second step), respectively. In isothermal desorption kinetics, the amount of hydrogen released of the doped sample was improved to 3.9 wt% in 2.5 h at 90 °C. Meanwhile, the undoped sample had released less than 1.0 wt% of hydrogen under the same condition. The activation energy of the LaFeO3-doped LiAlH4 sample was measured to be 73 kJ/mol and 90 kJ/mol for the first two dehydrogenation reactions compared to 107 kJ/mol and 119 kJ/mol for the undoped sample. The improvements of desorption properties were the results from the formation of LiFeO2, Fe and La or La-containing phase during the heating process.

BACKGROUND Chlorophyllin is used in traditional Chinese medicine because of its anticancer properties. This article describes the preparation and cytotoxic activity of a reduced chlorophyllin derivative (RCD) on tumour cell lines. MATERIALS AND METHODS RCD was prepared by reducing chlorophyllin with lithium aluminium hydride, and its solubility in the alkaline and organic phases are different from that of the parent compound chlorophyllin. RESULTS RCD also has different chromatographic behaviour from chlorophyllin on thin-layer chromatography and high-pressure liquid chromatography, and excitation and emission spectra. RCD has cytotoxic activity against ZR-75, MCF-7 and HT-29, human tumour cell lines. A clonogenic assay showed that the growth of tumour colonies on soft agar was reduced by RCD in a dose-dependent manner. CONCLUSION RCD is a novel compound exhibiting anticancer activity.

Hybrid propulsion offers safe, reliable and environment friendly alternative to conventional systems. There is a wide range of propellants and additives reported for hybrid propulsion. In this paper some energetic particles comprising metals, and light metal hydrides and their advantages in terms of regression behavior are discussed. Additive particles like aluminium, boron, boron carbide, tungsten, iron, carbon, magnesium, magnesium hydride, aluminium hydride, lithium aluminium hydride, ammonium perchlorate and ammonia borane are discussed. Regression rate enhancement of 20%-150% has been reported and found to be dependent on additive percentage. Metals have high density and heat of oxidation which helps in regression rate augmentation. Metal hydrides are good source of hydrogen varying from 7.6% for Magnesium hydride to 19.6% for Ammonia borane. These hydrides release nascent hydrogen during combustion and improve regression rate thereby boosting specific impulse and characteristic velocity of the rocket. Energetic particle laden hybrid rocket fuel has potential to make chemical propulsion safer, economical and sustainable.

Lithium aluminium hydride (LiAlH 4 ) is a promising hydrogen storage material with a storage capacity of 10.6 mass % H 2 . However, its practical use is hampered by the lack of direct rehydrogenation routes. In this study, we report on the confinement of LiAlH 4 into the nanoporosity of a high surface area graphite resulting in a remarkable improvement of its hydrogen storage properties. Nanoconfined LiAlH 4 started hydrogen desorption near 135 °C and after full dehydrogenation at 300 °C limited rehydrogenation was observed at the same temperature and 7 MPa of hydrogen pressure. Rehydrogenation took place through the formation of Li 3 AlH 6 with some limited rehydrogenation back to LiAlH 4 indicating the existence of different (de)hydrogenation paths upon nanoconfinement as compared to the known dehydrogenation path of bulk LiAlH 4 .

In this paper, we investigated the LiAlH4-reduction of 5-acetyl-1,6-dimethyl- 4-phenyl-3,4-dihydropyrimidin-2(1H)-one (N-methylated Biginelli compound). Following the reduction and SiO2-promoted dehydration, (Z)-5-ethylidene-1-methyl-6- methylene-4-phenyltetrahydropyrimidin-2(1H)-one was isolated as the major product (33% yield). Chromatographic separation of the reaction products also allowed us to isolate (yield in parentheses) and fully spectrally characterize: 1,6-dimethyl-4-phenyl- 5-vinyl-3,4-dihydropyrimidin-2(1H)-one (20%), 5-ethyl-1,6-dimethyl-4-phenyl-3,4- dihydro-pyrimidin-2(1H)-one (9%), 5-(1-hydroxyethyl)-1,6-dimethyl-4-phenyl-3,4- dihydropyrimidin-2(1H)-one (5%). A possible mechanism explaining the formation of these products is proposed.

Highly functionalized fluorenones were synthesized by an intramolecular cyclization of 2''-halo-[1,1':3',1''-terphenyl]-4'-carbonitriles in the presence of n-butyllithium or lithium aluminium hydride. The precursor was synthesized by ring transformation of 2-oxo-6-aryl/heteroaryl-4-(sec.amino)-2H-pyran-3-carbonitriles or 2-oxobenzo[h]chromenes with o-bromo/chloro/fluoro-acetophenone under basic conditions in moderate yield. We performed the control experiment to understand the proposed mechanism and found that the presence of a secondary amine in the starting material directs the reactivity. The photophysical properties of 3-methoxy-7-(piperidin-1-yl)-5H-indeno[2,1-b]phenanthren-8(6H)-one was explored and solvent dependent emission was observed. These compounds were also tested against HIV-1 and low to moderate activity was observed.

Trimeric betaine surfactants tri[(N-alkyl-N-ethyl-N-sodium carboxymethyl)-2-ammonium bromide ethylene] amines were prepared with raw materials containing tris(2-aminoethyl) amine, alkyloyl chloride, lithium aluminium hydride, sodium chloroacetate, and bromoethane by alkylation, Hoffman degradation reaction, carboxymethylation and quaternary amination reaction. The chemical structures of the prepared compounds were confirmed by FTIR, 1H NMR, MS and elemental analysis. With the increasing length of the carbon chain, the values of their critical micelle concentration initially decreased. Surface active properties of these compounds were superior to general carboxylate surfactants C10H21CHN+(CH3)2COONa. The minimum cross-sectional area per surfactant molecule (A min), standard Gibbs free energy adsorption (ΔG ads) and standard Gibbs free energy micellization (ΔG mic) are notably influenced by the chain length n, and the trimeric betaine surfactants have greater ability to adsorb at the air/water interface than form micelles in solution. The efficiency of adsorption at the water/air interface (pC20) of these surfactants increased with the increasing length of the alkyl chain. Their foaming properties, wetting ability of a felt chip, and lime-soap dispersing ability were also investigated.

A series of liquid polycarbosilanes were successfully synthesized by a sequential Grignard coupling reaction of (chloromethyl)triethoxysilane and vinylmagnesium bromide, followed by reduction with lithium aluminium hydride. The use of non-corrosive, easily handleable and storage stable (chloromethyl)triethoxysilane as starting material is an attractive advantage for this route. The as-synthesized polymers containing Si-CH=CH2 and Si - H groups are storage stable and can be easily cured in an inert atmosphere. The ceramic yield of the cured polycarbosilane and the C:Si ratio of the derived ceramic were varied by adjusting the mole ratio of starting materials in the feed. Among them, the polymer with a mole ratio of Si-CH=CH2 to Si - H of 1:10 has the highest ceramic yield at 89.6% after curing at 220 degrees C and the C:Si ratio of the derived ceramic is 1.48. This kind of polycarbosilane shows high potential as an SiC ceramic precursor in the fabrication of an SiC matrix by the precursor infiltration pyrolysis process. (c) 2015 Society of Chemical Industry

Polyhydroxylated piperidines are a functionally rich class of biologically active molecules that have broad therapeutic potential. Recently developed aza-[4 + 3] cycloadditions of putative aza-oxyallylic cations provide heterocyclic scaffolds that enabled a concise synthesis of polyhydoxylated piperidines. Chemoselective amide reduction and reductive hemiaminal ring opening was achieved in one pot by the action of aluminium hydride generated in situ via aluminium chloride and lithium aluminium hydride. Aziridinium ion mediated ring contraction and chloride displacement was triggered by silver acetate, followed by simple acetate hydrolysis using potassium carbonate to give four tetrahydropyridine diols. Olefin oxidation by osmium tetroxide installed the final hydroxyl groups, which yielded four novel polyhydroxylated N-alkoxypiperidines in good overall yield and high diastereoselectivity.

The heterogeneous reduction process for synthesis of poly(propylene imine) (PPI) dendrimer has been replaced by a novel and homogeneous process. Accordingly, to prepare half generations, acrylonitrile was added to amine groups via Michael addition reaction. Then, nitrile groups were reduced via homogeneous hydrogenation using lithium aluminium hydride to synthesize fifth-generation PPI dendrimers with ethylenediamine core. Also, peripheral primary amine groups were conjugated with folic acid (FA). Fourier transform infrared and 13C NMR spectroscopies and gel permeation chromatograph y were used to prove the synthesis of the various structures. Finally fifth-generation and FA-conjugated fifth-generation PPI dendrimers were loaded with doxorubicin and exposed to environments with different pH values to examine the release properties of the structures. Also, drug release kinetics was investigated by fitting experimental data with various release models. The synthesized dendritic structures showed Higuchi model release behaviour due to better solubility of drug in release media with respect to dendrimer cavities.

This chapter describes relevant chemical procedures used for purification of solvents and substances. Greater selectivity in purification can often be achieved by making use of differences in chemical properties between the substance to be purified and the contaminants. Unwanted metal ions may be removed by precipitation in the presence of a collector . Many classes of organic chemicals can be purified by conversion into suitable derivatives, followed by regeneration. Metal impurities can be determined qualitatively and quantitatively by atomic absorption spectroscopy, x-ray photoelectron spectroscopy, various mass spectrometric methods and/or inductively coupled plasma mass spectrometry. Reagents such as water, ammonia, hydrochloric acid, nitric acid, perchloric acid, and sulfuric acid can be purified via distillation using an all-glass still. Application of ion-exchange columns facilitate the removal of heavy metal ions such as Cu2+, Zn2+ and Pb2+ from aqueous solutions of many reagents and they are also useful for demineralising biochemical preparations such as proteins. In removing traces of impurities by precipitation, it is necessary to include a material to act as a collector of the precipitated substance so as to facilitate its removal by filtration or decantation. Metal hydrides, such as lithium aluminium hydride, calcium hydride, sodium borohydride and potassium borohydride are used extensively in the purification of chemicals. Because of the difficulty in regenerating the starting material, relatively few derivatives of organic substances are used for purification.

We demonstrate in-situ synthesis of homogeneously dispersed Ni-containing mesoporous carbon scaffold (Ni-MCS) for improving dehydrogenation kinetics of LiAlH4 (hereafter denoted as LAH). LAH was impregnated into Ni-MCS scaffold (LAH confined-Ni-MCS) and also into pure mesoporous carbon scaffold (MCS) (LAH confined-MCS). The XRD patterns of LAH confined in Ni-MCS system indicate its amorphous nature, while 27Al MAS NMR spectroscopy confirmed the nanoconfinement of LAH in the Ni-MCS system. TPD-MS demonstrated the released of H2 at 66°C for the LAH confined-Ni-MCS system, with 84°C reduction of the onset desorption temperature (Tonset) as compared to the pure LAH. The H2 desorption from LAH confined-Ni-MCS is about 6.19 wt% H2. This strategy enables the exertion of nanoconfinement, Ni catalyst and compartmentalization effects over the growth of particle size and aggregation, which also significantly contributed to reduce the activation energy (Ea) (39.67 kJ/mol) of the system.

Nearly quantitative mechanochemical synthesis of non-solvated AlH3 from lithium aluminium hydride (LiAlH4) and aluminium chloride (AlCl3) has been achieved at room temperature under reasonably low pressure of hydrogen (210 bar) or inert gas (125 bar for He or 90 bar for Ar). X-ray diffraction, solid-state 27Al NMR spectroscopy, and temperature programmed desorption analyses of as-milled materials reveal a nearly complete conversion of a 3 : 1 (molar) mixture of LiAlH4 and AlCl3 to a 4 : 3 (molar) mixture of AlH3 and LiCl in ca. 30 min. By applying pressure of 210 bar or less (depending on the gas: hydrogen, helium, or argon), competing reactions leading to formation of metallic aluminium can be completely suppressed. X-ray diffraction and NMR analyses of products extracted at various stages of the mechanochemical reaction between LiAlH4 and AlCl3 reveal, for the first time, that the solid-state transformation proceeds with LiAlCl4 as an intermediate. Evidently, the critical pressure required to suppress the formation of metallic aluminium depends on the rate at which mechanical energy is supplied during milling. For example, the critical pressure is reduced from 210 bar to 1 bar of hydrogen when the milling speed of a standard planetary mill is reduced from 300 rpm to 150 rpm, although at the expense of sluggish kinetics and much longer reaction time.

Lithium aluminium hydride reduction of bis-unsymmetric-diaryloxamides 3 is difficult to accomplish especially for the sterically hindered mesityl derivative. Using microwaves LAH reduction of 3a,d was successful in a short time, however, with cleavage of the ether linkage to give compounds 11a,d. Extension of this method enabled the reduction of bis-oxamide derivatives 13 to the corresponding tetraamine derivative 14 which was then converted to the bis-imidazolidinium salt 15. Application of this method led to rapid reduction of unsymmetric N,N'-diaryloxamides 16 to the corresponding N,N'-diarylethylenediamines 17 which were converted to their corresponding imidazolidinium salts 18.

Two series of new benzoxazepines substituted with different alkyl amino ethyl chains were synthesized comprising synthetic steps of inter and intramolecular Mitsunobu reaction, lithium aluminium hydride (LAH) reduction, debenzylation, bimolecular nucleophilic substitution (SN2) reaction. The present study investigates the effect of a tyrosine-based benzoxazepine derivative in human breast cancer cells MCF-7 and MDA-MB-231 and in breast cancer animal model. The anti-proliferative effect of 15a on MCF-7 cells was associated with G1 cell-cycle arrest. This G1 growth arrest was followed by apoptosis as 15a dose dependently increased phosphatidylserine exposure, PARP cleavage and DNA fragmentation that are hallmarks of apoptotic cell death. Interestingly, 15a activated components of both intrinsic and extrinsic pathways of apoptosis characterized by activation of caspase-8 and -9, mitochondrial membrane depolarization and increase in Bax/Bcl2 ratio. However, use of selective caspase inhibitors revealed that the caspase-8-dependent pathway is the major contributor to 15a-induced apoptosis. Compound 15a also significantly reduced the growth of MCF-7 xenograft tumors in athymic nude mice. Together, 15a could serve as a base for the development of a new group of effective breast cancer therapeutics.

A Diol with endocyclic structure that is 1-methyl-4-isopropyl-bicyclo [2,2,-2,3-two hydroxymethyl-5-Octene (MIBHO), deriving from terpene, was synthesized using the aid of lithium aluminium hydride (LAH) as reductant in THF media at 65 °C. The optimum synthesis conditions were confirmed by analysing the factors on reacting temperature, reacting time, different solvents and reductants. The molecular structure of the novel compound has been characterized by FT-IRGC-MS and 1H-NMR analysis. The data reveal that LAH could effectively reduce terpene maleic anhydride to corresponding alcohol, and the conversion rate of raw material could reach 84%.

Finding novel pathways for the reduction of carbon oxides is important for the ongoing search for new systematic entries to hydrocarbon feedstocks. The CO to formyl conversion with readily available hydrides represents an important step along this way. Using boranes as the reducing reagents is desirable and potentially useful. Reactions of trialkylboranes with carbon monoxide are synthetically established. H. C. Brown had shown that R3B systems readily react with CO at 100 to 125 8C at normal pressure to yield the respective tertiary alcohols after oxidative workup. They modified this procedure to achieve the synthesis of ketones and aldehydes. In the latter case lithium aluminium hydride reagents were added. However, carbon monoxide is surprisingly reluctant to be reduced with [B]H boranes. Carbon monoxide is reported to react with B2H6 at 100 8C and 20 atm to give “borane carbonyl” [H3B-CO], a gas (b.p. 64 8C) that dissociates at atmospheric pressure. We have now found that B H borane reduction of carbon monoxide can be carried out with a suitable borane at a frustrated phosphane/borane Lewis pair (FLP) template. We stirred a mixture of the bulky cyclopentenylphosphane 1 with the hydroboration reagent [HB(C6F5)2] [9] for about 15 minutes at RT and then subjected the resulting mixture to an atmosphere of carbon monoxide (2 bar). Workup after 12 h at RT eventually gave the reduction product 2 as a colorless solid in 63% yield (see Scheme 1). Single crystals of 2 were obtained from dichloromethane/n-pentane. In the crystal compound 2 contains a “h-formyl” B(C6F5)2 subunit that is bonded through the acyl carbon atom (C1) to the phosphorus atom and through the acyl oxygen atom (O1) to the boron center (B1) of the FLP framework (see Figure 1 and Table 1). The resulting six-membered heterocycle fea

Six novel hybrid carbazole (Cbz)–pyrrole (Pyr)-based carboxylated monomers were synthesised and unambiguously characterised using common spectroscopic tools. Clauson-Kaas, amide coupling, LAH (lithium aluminium hydride)-mediated reduction, esterification and debenzylation reactions were used as key chemical reactions towards their multi-step synthesis. The electro-oxidation features of all these six hybrid Cbz/Pyr-monomers were investigated for the electro-deposition of corresponding polyCOOH conducting coatings. Quite interestingly, and due to the fact that such electro-oxidisable monomers contain both types of oxidisable heterocycles, that is, Pyr and Cbz species, it was found that the successful electro-polymerisation of these hybrid Cbz/Pyr-monomers was highly dependent on the relative number of Cbz versus Pyr unit(s) present in corresponding monomers. Indeed, a successful electro-deposition of the corresponding conducting polymeric films onto a working Pt electrode was observed only for hybrid monomers characterised by a Cbz/Pyr unit(s) ratio greater than or equal to 1. This result has been validated by systematically tuning the number of oxidisable Cbz and Pyr unit(s) present in monomers through proper chemical design and monomer multi-step synthesis. In that case, cyclic voltammogram analyses readily confirmed the exclusive electro-deposition of conductingpolyCbz-films.

Background and aim [C]methyl iodide ([C]CH3I) is the most extensively used methylation agent for the preparation of a majority of C-labeled positron emission tomography (PET) radiotracers, which is commonly produced by the wet method and the gas-phase method. On account of the complexity of the gas-phase method, a simple automated synthesis of [C]methyl bromide ([C]CH3Br) as an analog of [C]CH3I is derived by the wet method in this study. Radiosynthesis of L-[S-methyl-C]methionine (MET), L-[S-methyl-C]cysteine (MCYS), [N-methyl-C]choline (CH), [C]methyl triflate ([C]CH3OSO2CF3), and [C]-2-β-carbomethoxy-3-β-(4-fluorophenyl)-tropane (CFT) by methylation reaction with [C]CH3Br, and PET imaging of patients are also described. Methods The preparation of [C]CH3Br by a one-pot wet method involved the following steps: reduction of [C]carbon dioxide with lithium aluminium hydride (LiAlH4) solution, treatment with hydrobromic acid, and distillation of [C]CH3Br under continuous nitrogen flow. [C]methylation of L-homocysteine thiolactone hydrochloride, L-cysteine, 2-dimethylaminoethanol, silver triflate, and nor-β-CFT as precursors with [C]CH3Br and purification with Sep-Pak cartridges gave MET, MCYS, CH, [C]CH3OSO2CF3, and CFT, respectively. In addition, PET imaging of brain cancer and Parkinson's disease was carried out. Results The uncorrected radiochemical yield of [C]CH3Br was (37.8±2.5%) based on [C]carbon dioxide within a total synthesis time of 10 min and the radiochemical purity of [C]CH3Br was greater than 95%. The uncorrected yields of MET, MCYS, CH, [C]CH3OSO2CF3, and CFT were 70.1±0.5%, 70.2±2.3%, 60.3±1.8%, 95.1±2.2%, and 60.1±1.5% (from [C]CH3OSO2CF3) within a total synthesis time of 2, 2, 5, 1, and 8 min, respectively. The radiochemical purity of MET, MCYS, CH, [C]CH3OSO2CF3, and CFT was more than 95%. Good PET images in the patients are obtained. Conclusion Automated synthesis of [C]CH3Br can be done by the wet method on the commercial [C]CH3I synthesizer. [C]CH3Br can be used for a [C]methylation reaction to produce C-labeled tracers for clinical PET imaging.

Several 1-arylisochromans were prepared from 1-bromoisochroman and 1-bromo-4,4-dimethylisochroman by reaction with arylmagnesium bromides. Bromination and heating yielded, presumably via bromo-1-arylisochromans, o-(bromoalkyl)benzophenones. Treatment with lithium aluminium hydride converted the ketones into the corresponding carbinols, the side-chain being simultaneously debrominated if sufficient hydride was used. Reactions of the bromoalkylbenzophenones with hydrazine derivatives yielded benzodiazepines. Treatment with hydriodic acid and red phosphorus converted 1-phenyl-isochroman into o-(2-iodoethyl)diphenylmethane while 4,4-dimethyl-1-phenyl-isochroman yielded 10,11-dihydro-10,10-dimethyl-5H-dibenzo[a,d]cycloheptene and a compound (C13H10)n of unknown structure.

Reaction of β-ionone with the dienynyl ether V under Neff conditions affords the C20 carbinol VI, from which vitamin A aldehyde VIII can be prepared by reduction with lithium aluminium hydride and subsequent hydrolysis of the complex of the reduced C20 carbinol with dilute acids. The dienynyl ether is synthesized from the acetal CH3COCH2CH(OCH3)2 by addition of propynyl-lithium, subsequent reaction of the resulting C7 carbinol II with ethyl vinyl ether to yield the C7 diacetal III and treatment of the latter with alkali amide in liquid ammonia. The overall yield of the dienynyl ether V is about 75%, while vitamin A aldehyde is obtained in yields of 55-60%, calculated on β-ionone.

Treatment of 3,4-benzoxanthone hydrazone with tetrahalogeno-α-benzoquinones gave the corresponding cyclic ethers (IIIa-b). Reductive cleavage of the latter with lithium aluminium hydride yielded 3,4-benzoxanthene together with the tetrahalogenocatechol. Whereas active hydrogen compounds effect cleavage of the dioxole ring in IIIa-b with the formation of the corresponding benzo-xanthylene, they react with 9-hydroxy-3,4-benzoxanthene yielding the benzoxanthyl derivatives (VIII). Diazoalkanes on 3,4-benzoxanthione afford the corresponding ethylene sulfides. The thermochromic properties of the ethylenes, obtained by the action of copper on the ethylene sulfides, are stressed. Reaction mechanisms are discussed.

The rearranged product resulting from the action of lithium aluminium hydride upon holarrhenine tosylate (IV) in ether solution has been tentatively formulated by Uffer as C-nor-D-homoconessine (V). We found that holarrhenine mesylate (III) is converted into the same rearranged product on reacting with sodium borohydride in refluxing alcohol. The spectroscopic analysis of the rearranged product confirms the proposal of Uffer and gives results which completely parallel those obtained by Lukacs et al. in their study on the product of the reaction of the sulfonic esters of 12β-hydroxyconanine1 with aluminium dichlorohydride. Further converging data are afforded by a reaction sequence involving consecutive Hofmann degradations of the rearranged product (V).

In the presence of hydrochloric acid and under oxygen purging, N-nitrosodimethylamine photolytically adds to 1-arylpropenes regiospecifically to give erythro- and threo-α-amino nitrates as the primary products which can then be reduced, using lithium aluminium hydride, to give α-amino alcohols or can undergo substitution reactions under photochemical conditions. The stereochemical courses of the addition, as well as the solvolysis of the diastereoisomeric α-amino nitrates with intramolecular amino group participation, are discussed in order to explain the product distributions.

The structure of a microbiological hydroxylation product of 17α,21-dihydroxy-9β,10α-pregn-4-ene-3,20-dione is found to be 11α,17α,21-trihydroxy-9β, 10α-pregn-4-ene-3,20-dione. This product is converted into 9β,10α-cortisone and to 9β,10α-hydrocortisone. Reduction of the 11-keto group with lithium aluminium hydride proceeds with the formation of 11β-hydroxy in minor quantity only. The stereochemistry of the 11-hydroxyl compounds is discussed on the basis of their nuclear magnetic resonance spectra.

For studies into the relationship between their physical properties and chemical structure, several polyunsaturated fatty acids related to (Z,Z,Z)-6,9,12-octadecatrienoic acid and (Z,Z,Z)-8,11,14-eicosatrienoic acid were synthesized. Methyl (E,Z,Z)-2,11,14-eicosatrienoate and methyl (E,Z,Z)-2,9,12-octadecatrienoate were prepared by E-stereoselective coupling of (methoxycarbonylmethylene)triphenylphosphorane with (Z,Z)-9,12-octadecadienal and (Z,Z)-7,10-hexadecadienal respectively. The synthesis of methyl (E,Z,Z)-4,9,12-octadecatrienoate started from 2,7-octadiyn-1-ol which was reduced with lithium aluminium hydride. The (E)-2-octen-7-yn-1-ol thus obtained was coupled with 1-bromo-2-octyne to give (E)-2-hexadecene-7,10-diyn- 1-ol. This was converted into 1-chloro-(E)-2-hexadecene-7,10-diyne, which via malonic ester synthesis yielded (E)-4-octadecene-9,12-diynoic acid. Stereospecific hydrogenation and esterification finally afforded the desired compound, from which methyl (E,Z,Z)-6,11,14-eicosatrienoate was obtained by chain elongation. Methyl (E,Z,Z)-6,9,12-octadecatrienoate was synthesized from 1,4-dichloro-(E)-2-butene which was converted into (E)-4-octen-7-ynoic-7-ynoic acid. Coupling the latter with 1-bromo-2-octyne, esterification and reduction yielded (E-4-hexadecene-7,10-diyn- 1-ol. Conversion into the corresponding chloro compound and stereospecific hydrogenation yielded 1-chloro-(E,Z,Z)-4,7,1 O-hexadecatriene. Malonic ester synthesis finally afforded the desired compound. The synthesis of methyl (E,Z,Z)-8,11,14-eicosatrienoate started from 2-octyne-1,8-diol which was reduced with lithium aluminium hydride; the resulting (E)-octene-1,8-diol was converted into 1,8-dichloro-(E)-2-octene. The latter was coupled with 1,4-decadiyne to give 1-chloro-(E)-6-octadecene-9,12-diyne, which was hydrogenated stereospecifically. Malonic ester synthesis finally completed the synthesis.

1,2,2-Trisubstituted aziridines have been prepared by reduction of secondary N-1-(2-chloroalkylidene)amines with lithium aluminium hydride. N-Substituted 1-azaspiro[2.5]octanes (spiroaziridines) have been synthesized by this method. Under appropriate gas chromatographic conditions, 1,2,2-trisubstituted aziridines underwent rearrangement to the corresponding secondary N-1-(alkylidene)amines. The reaction mechanisms are discussed.

Reaction of the anions of thebaine and 6-demethoxythebaine with 2-propanone gave the 5β-(dimethylmethanol)-substituted analogues 3 and 5 and the isomeric C-7-substituted morphinan-5,8-dienes 4, 6 and 7, respectively. No reaction took place with methanal. Therefore, thebaine-5β-methanol (10) was prepared by reacting the anion with alkyl chloroformate followed by lithium aluminium hydride reduction. Diels-Alder reaction of diene 10 with ethyl acrylate gave the 6α,14α-ethenoisomorphinan 11. Of the morphinan-6,8-dienes 3 and 5, only diene 5 showed a reaction, namely rearrangement followed by cycloaddition with ethyl acrylate, yielding three adducts. The structure of the major adduct 13 was elucidated using 1D- and 2D-NMR techniques and revealed an aporphine-like structure. Furthermore, the conversion of 11 into a new etorphine analogue 16 was accomplished by treatment with methylmagnesium bromide followed by 3-O-demethylation.

Heating 14β-bromocodeine (3) with methanol and triethylamine yielded 6α, 7α-epoxy-6-deoxyneopine (5). The epoxide 5 was reduced to neopine (7) with lithium aluminium hydride, whereas reaction of 5 with sodium methoxide gave 7β-methoxyneopine (9). Similar reactions were performed with 14β-bromo-5β-methylcodeine (4), yielding the corresponding 5β-methyl derivatives 6, 8 and 10. Acetylation of 3 and 4 gave 6α-O-acetyl-14β-bromocodeine (11) and its 5β-methyl analogue 12, respectively, from which the ortho esters 13 and 14 were obtained after treatment with methanol. Acid hydrolysis of 13 or, better, solvolysis of 11 in water yielded a mixture of 6α-O-acetyl-7α-hydroxyneopine (15) and 7α-acetoxyneopine (17). Under the same conditions 12 and 14 gave the 5β-methyl analogues 16 and 18.

The degradation of α-lupene to trisnorlupanone has been re-examined and analogous reactions with lupenyl acetate have yielded the corresponding C27 keto-acetate. Conclusive evidence of the presence of a carbonyl group in these compounds has been obtained by spectrographic methods and by lithium aluminium hydride reduction.

A method is described for the preparation of pyridylaldehydes (pyridylmethanals), as well as of several derivatives of these compounds, some of which have not hitherto been mentioned in the literature. The aldehydes were obtained from the corresponding pyridinecarboxylic acids, which were esterified, the ethyl esters reduced with lithium aluminium hydride to the pyridylmethanols and the latter in turn oxidized with lead tetra-acetate in benzene solution.

In a model study directed towards the synthesis of 5,10-diazasteroids, piperidazine was condensed with 2-methoxycarbonylmethylcyclohexanone (2) to give decahydro-Δ7a(11a)-6-oxopyridazo[1,2-a]cinnoline (4). Reduction of 4 with lithium aluminium hydride yielded decahydro-Δ7a(11a)-pyridazo[1,2-a]cinnoline (5). Subsequent reduction of 5, either catalytically or with sodium borohydride, proceeded stereospecifically to the perhydropyridazo[1,2-a]cinnoline (8), with B/C cis ring fusion.

The lithium aluminium hydride reduction of N-2-(1,1-dichloroalkylidene)-anilines 3 afforded mainly the rearranged secondary amines 4 next to the normally expected secondary amines 5. The formation of the rearranged secondary amines 4 is explained by an aziridine intermediate. The highly branched derivative 3d gave the aziridine 6d in good yield, besides the secondary amine 5d.

Experimental evidence is provided that the rearrangement of N-aryl α,α-dichloroketimines with lithium aluminium hydride in ether, observed as a competitive reaction during the stereospecific synthesis of cis-aziridines, proceeds via consecutive transformation of α-chloroaziridines into azirinium chlorides and α-imidoylcarbenium ions, the latter being trapped by chloride anion to afford β-chloroenamines, which furnish rearranged anilines on treatment with lithium aluminium hydride.

Treatment of N-1-(2-chloro-2-methylpropylidene) amines with potassium cyanate in methanol afforded 1-substituted-4-methoxy-5,5-dimethyl-2-imidazolidinones, which were easily converted into the non-methoxylated derivatives, i.e. 1-substituted-5,5-dimethyl-2-imidazolidinones, by reaction with lithium aluminium hydride in diethyl ether. The structure was confirmed by independent synthesis of the latter heterocycles and their isomeric structure (4,4-dimethyl derivative). The formation of the 2-imidazolidinones, starting from α-chloroaldimines and potassium cyanate, involved a rearrangement of the imino-nitrogen atom, which was explained by an aziridine intermediate.

A general synthetic route to N-1-(2,2-dichloroalkylidene) amides is described, starting from aliphatic 2,2-dichloroaldehydes and an appropriate N-unsubstituted amide. The adducts thus formed were converted into N-(1,2,2-trichloroalkyl) amides with thionylchloride and subsequently dehydrohalogenated with triethylamine. These N-acyl α,α-dichloroaldimines were found to be very apt to nucleophilic addition at the activated carbon-nitrogen double bond, producing stable adducts. The configuration of the adducts in solution was determined by NMR-spectroscopy. Treatment of the title compounds with lithium aluminium hydride in diethylether afforded 1,2-dialkylaziridines. The reactivity of these N-acyl α,α-dichloroaldimines was compared with the reactivity of the N-alkyl analogues and the corresponding oxygen analogues, i.e. α,α-dihalogenated aldehydes.

A non-catalytic reduction of α-oximinoketones 1 and α-oximinoalcohols 2 to erythro-2-amino-1-arylalkan-1-ols 3 with lithium aluminium hydride is reported. The erythro-2-amino-1-arylalkan-1-ols are isolated as their hydrochlorides 5 and characterised as the erythro isomers by benzoylation.

3-(Trichlorogermyl)propanoic acid (1a) reacts with phenylmagnesium bromide in molar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a). In the compounds 1a and 2a the β-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide. The compound 1a reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give 1,1-diphenyl-3–(triphenylgermyl)propanol (4a). The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also. Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy. Moreover, the compound la reacted with phenylmagnesium bromide in molar ratio 1:6, then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3 (triphenylgermyl)-1-propene (5a) in one pot reaction. Alkyl Ge–C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride (LiAlH4) in good yield.

Synthesis of p-methoxy-cynnamil-p-methoxy-cinnamate, (PMS)2O from ethyl-p-methoxy-cinnamate (EPMS) from dry rhizome of kaempferia galanga L as sunscreen compound have been done. Isolation of EPMS was done by percholation using ethanol 96 % and recrystallitation using methanol to have 2.2 % yield. Hydrolysis of EPMS using alcoholic KOH resulted methoxycinnamic acid (APMS) of 90.26 % yield. Reduction EPMS using lithium aluminium hydride in dry ether would give p-methoxycinnamoyl alcohol (PMS-OH) of 41.98 % yield. Then reaction of p-methoxycinnamoyl chloride (PMS-Cl) and PMS-OH in chloroform would produce p-methoxycinnamoyl p-methoxycinnamate ((PMS)2O) of 1.77 % yield. All compound were identified by TLC and several spectrometry methodes i.e. U.V Vis, IR, 1H-NMR and GC-MS Keywords: esther cinnamate, sunscreen, Kaempferia galanga.

The title compound 3,4-benzocycloocten-1,5-diyne (1) is a highly reactive hydrocarbon that has been shown to undergo addition reactions with tetraphenyl-cyclopentadienone (tetracyclone) to the 2:1 adduct 6, with octacarbonyldicobalt to the bis metal complex 7, with lithium aluminium hydride to the bis diene 9, and with various electrophilic reagents. In these latter cases cationic intermediates are generated from 1 and a transannular cyclization takes place leading to novel derivatives of 1,2-dihydropentalene (31, 32, 35, 36, 43, 44).

The regioselective reduction of substituted 1-bromo-2-trifluoroacetylcyclobutenes by lithium aluminium hydride affords corresponding brominated alcohols, which, under the treatment of two equivalents of butyllithium, give new lithiated cyclobutenes. Their carboxylation followed by lactonization induced by trifluoroacetic anhydride appeared to be an effective approach towards 5-trifluoromethylated furanones condensed with substituted cyclobutene rings.

Sporopollenin, which is a naturally occurring and highly resilient organic polymer constituting the external shell of spores and pollen grains, has been converted into a primary amine form with a loading of 0.58 ±0.04 mmol.g−1 by reductive amination with ammonia and lithium aluminium hydride successively. The presence of the amine and precursor amide groups were established by combustion elemental analysis, ICP-OES, FTIR, solid-state NMR and reactivity of the primary amine group to salt formation and nucleophilic addition and substitution with phenyl isothiocyanate and benzene sulfonyl chloride, respectively. This relatively simple conversion has served to provide further information regarding the presence and reactivity of carboxylic acid functions on this relatively uncharted polymer and offers aminosporopollenin as a new material for potential solid-phase applications.

1,3-Di-O-acetyl-4-O-benzyl-2,6-dideoxy- d -arabinopyranose (11) was synthesised from thiophenyl α- d -mannopyranoside (21) in an eight-step sequence. Tosylation of 21 and subsequent reaction with 2,2-dimethoxypropane gave tosylate 22, which upon treatment with lithium aluminium hydride furnished 6-deoxy glycoside 24 and by-product thiophenyl 6-deoxy-2-O-isopropyl-α- d -arabinopyranoside. The X-ray crystal structure of the latter was determined. Benzylation of the 4-hydroxyl group of 24 and subsequent protecting group manipulation gave d -rhamnosyl bromide 29, which on treatment with zinc–copper couple gave the orthogonally protected d -rhamnal 30. Triphenylphosphine hydrogen bromide catalysed addition of acetic acid to 30 furnished the target molecule 11. The scandium(III) triflate promoted reaction of 11 and 2-naphthol gave the corresponding C-glycoside 36 in 86% yield.

An improved synthesis of [1.1]ferrocenophane-1,12-dione (2) by oxidation of [1.1]ferrocenophane with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) is presented. The syn conformer of dione 2 is structurally characterized. The compound undergoes various addition reactions at the bridging carbonyl groups. Attempts to add 1,1'-dilithioferrocene result, however, in the diadduct 9, not in the symmetric trinuclear diol 8. Reaction of 2 with sodium cyclopentadienide in the presence of aluminium trichloride (AlCl 3 ) gives the respective difulvene 11 in excellent yield. The dynamic behavior of 11 is investigated by variable temperature 1 H NMR measurements (VT-NMR). The cyclovoltammogram of 11 indicates two reversible oxidation steps. Reduction of difulvene 11 with lithium aluminium hydride (LiAlH 4 ) results in the formation of [1.1]ferrocenophane 12 with cyclopentadienyl anion substituents at either one of the two bridges. While attempts to generate a third ferrocene moiety by reaction with iron(II) choride (FeCl 2 ) have failed so far, the formation of 12 is established by protonolysis and methylation reactions.

Condensation of 2-methyl-1-pyrroline with chloroacetone or 3-chloro-2-butanone using LDA in THF afforded novel 2-(3-hydroxy-2-methyl-1-alkenyl)-1-pyrrolines via a peculiar reaction mechanism instead of the anticipated 2-(3-oxobutyl)-1-pyrrolines. The intermediacy of 2-(2,3-epoxy-2-methylalkyl)-1-pyrrolines in the latter transformation was demonstrated by immediate reductive epoxide ring opening utilizing lithium aluminium hydride in diethyl ether. Furthermore, 2-(3-oxobutyl)-1-pyrroline was prepared via an alternative approach through alkylation of 2-methyl-1-pyrroline with 3-chloro-2-(methoxymethyloxy)-1-propene using LDA in THF, followed by acid hydrolysis. Reduction of 2-(3-oxobutyl)-1-pyrroline by sodium borohydride in methanol afforded the corresponding 2-(3-hydroxybutyl)-1-pyrroline in good yield.

Four racemic nicotine isotopomers, doubly labelled with stable isotope, were prepared for use in studies of plant metabolism. First, starting from halogeno nicotinates, one deuterium was introduced into the pyridine moiety by reductive dehalogenation with zinc, and choosing deuterated acetic acid as the acidic medium. Pyridine 2H-labelled nornicotine derivatives were then formed in two reaction steps, a condensation reaction with N-vinylpyrrolidinone followed by catalytic hydrogenation. The deuteromethylation of these monodeuterated nornicotines was achieved by reduction of the corresponding ethyl carbamates with deuterated lithium aluminium hydride. The four regioisotopomers obtained were at the least 90% labelled on each site, sufficient for the metabolic studies envisaged. Copyright © 2009 John Wiley & Sons, Ltd.