One-Step Preparations

These methods permit simultaneously the preparation of the support and the deposition of gold. 

It is important to carefully wash the samples to remove Na and Cl. This is possible by washing in water at 80°C [107, 108]. This method is valid for a limited number of supports, depending on the respective precipitation rates of support metal hydroxide and gold hydroxide, which is supposed to precipitate as such their reciprocal affinity determines the gold particle size [22,109]. 

The zinc and gold hydroxides precipitate roughly at the same pH ( 7). In the case of Au/Fe203, the iron/hydroxide precipitates at lower pH ( 3), that 

The sol-gel method does not seem to provide small gold particles on oxide supports ( 20 nm), but it seems more suitable for oxides with mesoporous structures [7]. 

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By similar procedures diazirines were prepared not only from simple aliphatic ketones but also from hydroxyketones and )3-aminoketones (B-67MI50800), and so were a large number of diazirines from steroidal ketones (65JA2665). Permanganate, bromine, chlorine and hypochlorite were used as oxidants. A one-step preparation of diazirines from ketones like 3-nonanone, ammonia and chlorine has been claimed in a patent (66USP3290289). 3,3-Diazirinedicarboxylic acid derivatives like (286) were obtained directly from oxime tosylates by the action of two moles of O-ethoxyamine (81AG(E)200). 

Nelson and Scliut investigated the reaction of 5a-cholestanone (lb) with diazomethane in a search for a direct, one-step preparation of A-homo ketones. Using a large excess of diazomethane generated in situ from A-methyl-nitrosourea with potassium hydroxide in ether-methanol at 0°, 5a-cholestanone (lb) is converted into the 7-membered ring homolog (3b) as the predominant product. Both theoretically possible A-homo ketones can be expected with an unsymmetrically-substituted cyclohexanone such as 5a-cholestanone (lb). 

The same amino compounds also underwent reactions with a series of 3-cyano-4-imino- and 3-cyano-4-oxo-piperidines to yield 4-amino-5,0,7,8-tetrahydropyrido[4,3-d]pyrimidines. . A tetra-hydropyTido[4,3-prepared from 4-amino-l-henzyl-3-cyano-d -piperidine (134) hy a simple one-step preparation. This method is of general application for the preparation of fused pyrimidines and previous papers in this field are listed by Taylor. ... 

Parish, C. A. et al. (1998). Isolation and one-step preparation of A2E and iso-A2E, fluorophores from human retinal pigment epithelium. Proceedings of the National Academy of Sciences 95 2988-2995. 

Xiaomin, N., Xiaobo, S., Huagui, Z., Dongen, Z., Dandan, Y. and Qingbiao, Z. (2005) Studies on the one-step preparation of iron nanopartides in solution. Journal of Crystal Growth, 275 (3—4), 548-553. 

Okamoto, Y., Azuhata, T., and Sakurai, H., Dialkyl 3-alkoxy-3-(trimethylsi-loxy)-2-propenephosphonate a one step preparation of (dialkoxyphosphi-nyljmethyl-substituted ketene alkyl trimethylsilyl acetal, Chem. Lett., 1265, 1981. 

Kitahara et al. decided on a classical approach for generating the bentho-cyanin A skeleton [85]. Following Hollimann [86] they started their synthesis with the one-step preparation of the phenazine 106 by reaction of 100 and... 

Method This method is attractive owing to the easy one-step preparation of the starting ditelluride. The reaction can be rationalized via an aryltellurenyl bromide as an intermediate. 

Sorbitol easily dehydrates into its 1 4-3 6-dianhydro derivative, isosorbide (III), in the presence of an acid catalyst such as sulfuric, hydrochloric, or toluenesul-fonic acid or a cation exchange resin in a one-step preparation in high yield (75-85%)(1) ... 

Extension to cyclic Michael donors also met with marked success using imida-zolidine catalyst 54 (10 mol%) (Scheme 22) [95]. Conveniently, the reactions proceeded at room temperature using dichloromethane as the solvent and 1.05 equivalents of the Michael donor, representing a substantial improvement in the atom efficiency of the process. The synthetic utility of this transformation was exemplified by the one-step preparation of the anticoagulant (5)-warfarin (R = Ph, = Me, R = H 90% yield 80% ee) which could be recrystallised to optical purity (>99.9% ee) from acetone/water. 

An example of a direct (one-step) preparation involving aliphatic nucleophilic substitution with [ F]fluoiide is the synthesis of [ F]fallypride (Scheme 34), a high-affinity dopaminergic D2 receptor ligand, from the corresponding tosylate in about 20% radiochemical yield [145],... 

Kohn et developed a one-step preparation of a stable carboxylic-sulfinic acid anhydride by oxidizing 3,3,4,4-tetraphenyl-) -propionothiolac-tone with a peracid (Eq. 50). 

The assembly of functionalized nanostructured silica with uniform pore channels using neutral alkylamine surfactants (S°I° -> HMS) and non-ionic alkylpolyethyleneoxide surfactants (N°I° —> MSU-X) provides many advantages over conventional electrostatic assembly pathways (S+f, etc.). In contrast with electrostatically assembled MCM-41-type materials, mesostructured adsorbents produced by non-electrostatic assembly methods typically possess pore channel structures and particle morphologies which improve their ability to interact with targeted adsorbate species. Moreover, non-electrostatic assembly pathways are well-suited for the direct synthesis of functionalized mesostructured silica by one-step preparation processes under ambient temperature, neutral pH conditions. The environmental application of such materials for the treatment of mercury-contaminated water is also demonstrated. 

Figure 5.7. One-step preparation of vinylpolystyrene from Merrifield resin [63].

The direct one-step preparation of 2-acetamido-3,4,6-tri-0-acetyl-2 -deoxy-a-D-glu copyranosyl chloride was reported by Micheel and co-workers,3 and the described procedure is essentially the method of Horton and Wolfrom.4 The product was first prepared through a two-step route from 2-amino-2-deoxy-D-glucose hydrochloride by Baker and co-workers,5 and a number of adaptations of this method have been described6-8... 

Table II. Ingredients of One-Step Preparation of Cured Polyester...

S. Abouhilale, J. Greiner, and J. G. Riess, One-step preparation of 6-perfluoroalkylalkanoates of trehalose and sucrose for biomedical uses, Carbohydr. Res., 212 (1991) 55-64. 

D. R. Hicks and B. Fraser-Reid, Selective sulphonylation with A-tosylimidazol. A one-step preparation of methyl 2.3-an hydro-4,6-0-benzylidene- -i)-mannopyranoside,... 

O. Mitsunobu, T. Kudo, M. Nishida, and N. Tsuda, Stereospecific and stereoselective reactions. 4. A one-step preparation of 2,3-anhydro-4,6-0-bcnzylidcnc- -i)-allopyrano-side and -gulopyranoside, Chem. Lett., (1980) 1613-1614. 

P-Lactones alkenes.1 A new one-step preparation of 3-lactones is based on the fact that the enolates of phenylthiol esters react with carbonyl compounds to form (3-... 

The one-step preparation of y-butyrolactones starting from an acyclic a-iodo ester was also investigated by using the polymer-supported distannane 90 as radical source. The y-butyrolactone was formed in 35% yield and contained 61% of the reduced a-haloester166 (Scheme 45). 

The latter approach has been exemplified in a number of published cases. An indication of the development requirements of well-known reactions for successful employment in array synthesis is provided by the work ofWatson and co-workers [15] to prepare thiazole derivatives. Adaptation of the Hantzch synthesis of 2-aminothiazoles (Fig. 2) from a-haloketones and thioureas was used in the one-step preparation of discrete samples. Inclusion in the array of a compound of known biological activity provided a valuable internal control. 

Chung, C. T., Niemela, S. L and Miller, R. H. (1989) One-step preparation of competent Escherichia coli transformation and storage of bacterial cells in the same solution. Proc. Natl. Acad. Sci. USA 86, 2172-2175. 

A three-component palladium-catalyzed cascade process has been employed by Grigg and co-workers for the one step preparation of 3-substituted isoindohn-l-ones 103 [91]. This cascade reaction involves Pd-catalyzed car-bonylation of aryl iodide 102 and subsequent trapping of the acyl palladium species by an amino derivative. The resulting amide undergoes an intramolecular Michael addition leading to the bicyclic systems 103 isolated in moderate to good yields (Scheme 39). 

Biehl and coworkers170 have described a facile one-step preparation of substituted 3-benzyl-l-hydroxynaphthalene-2-carbonitriles 301 and 11 -amino-5//-an thra[2,3-... 

Talsma, H., Van Steenbergen, M. J., Borchert, J. C. H., Crommelin, D. J. A. (1994), A novel technique for the one-step preparation of liposomes and nonionic surfactant vesicles without the use of organic solvents. Liposome formation in a continuous gas stream The bubble method,/. Pharm. Sci., 83, 276-280. 

Luo L, Eisenberg A (2002) One-step preparation of block copolymer vesicles with preferentially segregated acidic and basic corona chains. Angew Chem Int Ed Engl 41 1001-1004... 

The dibenzo derivative of a cyclic acetylenic silane 96 was synthesized by mono-deprotonation of 1,2-diethynyl-benzene with 1 equiv of lithium hexamethyldisilazide (LiHMDS) followed by treatment with 0.5equiv of dichlor-odiphenylsilane (formation of 95). A repeat of the deprotonation step, followed by silylation cycle, gave 96 in 77% yield after column chromatography (Scheme 19). One-step preparation of 96 using 2 equiv of base and 2 equiv of the silylation agent also yielded the desired product, however, the yield was 50% of those of the previous method... 

Reductive dehalogenation is an efficient method of synthesis of cyclopropanes spiroannulated to five- and higher-membered carbocycles (i.e. compounds in which spiroannulation does not result in accumulation of extra strain) . The required gem-(dihalomethyl)cycloalkanes are usually prepared by halogenation of the precursor diols (equation 1). The cyclization is most efficiently accomplished in the Zn-alcohol-water system . For example, spiro[2.5]octane 7 was prepared in 91% yield using this procedure. This method is useful even for a one-step preparation of bis-spirocyclopropyl compounds as exemplified in equation 2. However, the application of the reductive dehalogenation method to the synthesis of more strained SPC (i.e. spirohexane or spiropentane) often leads to rearranged products. For example, methylenecyclopentane was the only product obtained from bis(bromomethyl)cyclobutane (equation 3) ... 

In a subsequent investigation by the author, a one-step preparation of the Step 1 reagent was prepared by the condensation of cyclohexylketone with 4-methoxyphenylacetonitriIe, potassium hydroxide, and tetrabutylammonium iodide (2). 

Thallium(in) sulfate in water brings about the anti hydroxylation of 3-r-butyl- and 4-r-butyl-cyck>-hexene. The reagent has been recommended for the one-step preparation of rranj-diols from ctmfor-mationally rigid cycloalkenes. 

Further details have been presented of the one-step preparation of vitamin K analogues through the use of -cyclodextrin extrusion catalysts. A paper has appeared dealing with the photoreduction of vitamin K [phylloquinone (229)]. ... 

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