Oxide one-pot synthesis

A novel, soluble trimetallic double alkoxide precursor to potassium aluminosilicate (KAlSi04) has been synthesized by a one pot procedure and its structure characterized. The process termed the oxide one pot synthesis (OOPS) process uses simple, inexpensive chemicals, silica and aluminum hydroxide, to form a processable precursor in one simple step. The precursor is relatively stable to moisture and can be handled in air for long periods of time with minimal hydrolysis. On pyrolysis in air, to 1100" C, it produces phase-pure KAlSi04. The proposed precursor was characterized using thermogravimetric analysis, multinuclearNMR, and mass spectroscopy. The results suggest the precursor disproportionates in solution. 

We recently reported the discovery of a general, low cost route to alkoxide precursors to aluminosilicates (spinel, mullite and cordierite), by direct reaction of any stoichiometric mixture of Si02, A1(0H)3 and group I/II metal hydroxides with triethanolamine (TEA) in ethylene glycol (EG) solvent (77). This process, termed the oxide one pot synthesis (OOPS) process provides stable, processable precursors to phase pure ceramic materials. A general reaction for the synthesis of OOPS derived precursors is given by ... 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

Oxidation of 4H-pyran-4-thiones with thallium(III) trifluoroacetate was used in the one pot synthesis of l,6-dioxa-6n-thiapentalenes, a hypervalent heterocyclic system [57] (equation 27)... 

This reaction gives good results for a variety of activated and unactivated alkyl halides [112] Oxidation of 2-bromoketones with iV-phenyltriflamide was used m a one pot synthesis of pyrazines by the sequence of reactions shown m equation 57 [II3] The procedure was successfully applied to the synthesis of deoxyaspergilhc acid [II4 ... 

A one pot synthesis of isoxazolines 78a-f involves base mediated 1,4-addition of malonate or alcohol 76 possessing an allylic substituent, conversion of the resulting nitronate to the a-chloroaldoxime (hydroxymoyl chloride 77) and its subsequent dehydrohalogenation to the nitrile oxide intermediate which cyclizes to isoxazoline 78 (Eq. 7, Table 6) [32]. 

Choudary, B.M., Chowdari, N.S., Mahdi, S., Kantam, M.L. (2003) A Trifimctional Catalyst for One-Pot Synthesis of Chiral Diols via Heck Coupling-N-Oxidation-Asymmetric Dihydroxyla-tion Application for the Synthesis of Diltiazem and Taxol Side Chain. Journal of Organic Chemistry, 6S, 1736-1746. 

Hassner and coworkers have developed a one-pot tandem consecutive 1,4-addition intramolecular cycloaddition strategy for the construction of five- and six-membered heterocycles and carbocycles. Because nitroalkenes are good Michael acceptors for carbon, sulfur, oxygen, and nitrogen nucleophiles (see Section 4.1 on the Michael reaction), subsequent intramolecular silyl nitronate cycloaddition (ISOC) or intramolecular nitrile oxide cycloaddition (INOC) provides one-pot synthesis of fused isoxazolines (Scheme 8.26). The ISOC route is generally better than INOC route regarding stereoselectivity and generality. 

I.2. Oxidation of Amines Oxidation of primary amines is often viewed as a particularly convenient way to prepare hydroxylamines. However, their direct oxidation usually leads to complex mixtures containing nitroso and nitro compounds and oximes. However, oxidation to nitrones can be performed after their conversion into secondary amines or imines. Sometimes, oxidation of secondary amines rather than direct imine oxidation seems to provide a more useful and convenient way of producing nitrones. In many cases, imines are first reduced to secondary amines which are then treated with oxidants (26). This approach is used as a basis for a one-pot synthesis of asymmetrical acyclic nitrones starting from aromatic aldehydes (Scheme 2.5) (27a) and 3,4-dihydroisoquinoline-2-oxides (27b). 

A one-pot synthesis of 3,3-disubstituted indolines was achieved by taking advantage of a sequential carbopalladation of allene, nucleophile attack, intramolecular insertion of an olefm and termination with NaBPh4 (Scheme 16.6) [10]. First, a Pd(0) species reacts with iodothiophene selectively to afford ArPdl, probably because the oxidative addition step is facilitated by coordination with the adjacent sulfur atom. Second, the ArPdl adds to allene, giving a Jt-allylpalladium complex, which is captured by a 2-iodoaniline derivative to afford an isolable allylic compound. Under more severe conditions, the oxidative addition of iodide to Pd(0) followed by the insertion of an internal olefm takes place to give an alkylpalladium complex, which is transmetallated with NaBPh4 to release the product. 

Two possible interesting acetals are diethoxy ethane or butane. They can be synthesized by the catalyzed reaction of acetaldehyde (obtained by ethanol catalytic oxidation) with two molecules of ethanol, or by the catalyzed reaction of butanal (obtained by catalytic conversion of two molecules of acetaldehyde) with two molecules of ethanol. To achieve a one-pot synthesis, a key aspect for a possible commercial development, it is necessary to develop suitable multifunctional catalysts. Research on these aspects is in progress [63]. 

In a one-pot synthesis of thioethers, starting from potassium 0-alkyl dithiocarbonate [36], the base hydrolyses of the intermediate dialkyl ester, and subsequent nucleophilic substitution reaction by the released thiolate anion upon the unhydrolysed 0,5-dialkyl ester produces the symmetrical thioether. Yields from the O-methyl ester tend to be poor, but are improved if cyclohexane is used as the solvent in the hydrolysis step (Table 4.13). In the alternative route from the 5,5-dialkyl dithiocarbonates, hydrolysis of the ester in the presence of an alkylating agent leads to the unsymmetrical thioether [39] (Table 4.14). The slow release of the thiolate anions in both reactions makes the procedure socially more acceptable and obviates losses by oxidation. 

It is quite often possible to prepare hydroxypyridinone complexes directly by one-pot synthesis from the appropriate hydroxypyranone, amine, and metal salt 90-92). They can also be prepared by reacting complexes such as P-diketonates with hydroxypyridinones (see e.g., Ce, Mo later). Several maltolate complexes, of stoichiometry ML2, ML3, ML4, or MOL2, have been prepared by electrochemical oxidation of the appropriate metal anode, M — a first-row d-block metal (Ti, V, Cr, Mn, Fe, Co, Ni), In, Zr, or Hf, in a solution of maltol in organic solvent mixtures 92). Preparations of, e.g., manganese(III), vanadium(III), or vanadium(V) complexes generally involve oxidation... 

Both uncalcined and calcined LDHs have also been shown to be effective supports for noble metal catalysts [18-25]. For example, palladium supported on Cu/Mg/Al LDHs has been used in the liquid phase oxidation of limonene [24], and on calcined Mg/Al LDHs for the one-pot synthesis of 4-methyl-2-pentanone (methyl isobutyl ketone) from acetone and hydrogen at atmospheric pressure [25]. In the latter case, the performance depends on the interplay between the acid-base and hydrogenation properties. More recently. 

Shen L, Zhang J, Cao S, Yu JL, Liu NJ, Wu JJ, Qian XH (2008) One-pot synthesis of trifluoromethyl-containing pyrazoles via sequential Yb(PFO)(3)-catalyzed three-component reaction and IBX-mediated oxidation. Synlett 3058-3062... 

Lieby-Muller E, Simon C, Imhof K, Constantieux T, Rodriguez J (2006) A multicomponent domino reaction and in situ aerobic oxidation sequence for the first one-pot synthesis of polycyclic benzimidazoles from 1,3-dicarbonyl derivatives. Synlett 1671-1674... 

Nitrile oxides were also readily generated by reaction of aldoximes 172 with icri-butyl hydroperoxide and bis(tributyltin) oxide. The reaction proceeded nnder mild conditions, in which 0-stannylated aldoximes 173 were the key intermediates. This reaction system was applicable to the one-pot synthesis of isoxazoline 174 or isoxazole 175 derivatives... 

Savitha G, Perumal PT (2006) An efficient one-pot synthesis of tetrahydroquinoline derivatives via an aza Diels-Alder reaction mediated by CAN in an aqueous medium and oxidation to heteroaryl quinolines. Tetrahedron Lett 47 3589-3593... 

Highly monodisperse CdSe/CdS core/shell nanoparticles have been prepared by thermolysis in tri-n-octylphosphine oxide (TOPO) using [Cd(Se2CNMe( Hex))2] (250 °C for 30 min) and [Cd(S2CNMe( Hex))2] (250 °C for 30 min) as single-molecule precursors in a one-pot synthesis [118,119]. [Cd(Se2CNMe(Hex))2] (0.8 g) was dissolved in trioctylphos-... 

An oxidative coupling reaction of hydroxypyridinones with /5-dicarbonyl compounds leads to the formation of dihydrofuro[3,2- ]pyridinone derivatives (Equation 48) <2005TL5085>. The reaction is carried out as a one-pot synthesis. 

A phosgene-free route to aromatic isocyanates, such as M DI and TDI, was reported by Fernandez et al. [42] (Scheme 5.7) According to the patent, the one-pot synthesis involves the use of an immobilized Schiff base type of ligand catalyst that facilitates the oxidative carbonylation of aromatic amines to the corresponding isocyanates. However, 2,2,2-trifluoroethanol (TFE), 1,2-dichlorobenzene, and carbon monoxide were used in this process, so this would not be a totally environmentally friendly process even if these reagents could be recycled and reused. 

An alternative approach to the oxidative rearrangement uses chlorine as the oxidant in a one-pot synthesis (80JOC1109). Not only does this reagent convert the furan to the pyran-3-one, but it takes the latter to the 4-halogeno derivative via the labile 3,4-dihalogeno compound. The pyran-4-one is obtained by an in situ acid-catalyzed hydrolysis. The overall yield of maltol is over 60%, and ethylmaltol is obtained in a similar conversion from ethylfurfuryl alcohol. 

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