One-step condensation

The one-step condensation of phenacyl bromide on dithiomalonanilide (method D) leads to A -phenyl thiazolocyanines (Scheme 37),... 

The one-step condensation to convert 2-butanone, ethyl cyano-acetate, and hydrocyanic acid to ethyl 2,3-dicyano-3-methyl-pentanoate is a modification of the procedure described by Smith and Horowitz 6 in which pyridine acetate was employed as the catalyst. Higson and Thorp 6 employed a two-step procedure in which butanone was converted to its cyanohydrin, which in turn was condensed with ethyl cyanoacetate. 

In the 1,4-benzoxathiane series, neither dehydration of the hydroxy compound (189) nor elimination of ethanol from (190) give very satisfactory yields of (184) and once again the best yield (76%) is obtained by pyrolysis of the 2-acetoxy derivative (191). 3-MethyI-l,4-benzoxathiin is obtained by an analogous route, but 2,3-diphenyl-l,4-benzoxathiin is conveniently prepared by a one-step condensation of 2-mercaptophenol and benzoin in 21% yield <66HC(21-2)852>. 

In addition, Song et al. (76) used a one-step condensation synthesis method to prepare the PLA-MWCNTnanocomposites. For detailed experimental conditions, refer to Song et al. (76). The nanocomposites were prepared using pure and carboxylic-acid-functionalized MWCNTs. As with the other studies, the carboxylic-acid-functionalized MWCNTs dispersed better in PLA compared with non-functionalized MWCNTs. Overall, it can be inferred from the studies described in this section that the functionalization of MWCNTs is a very important step in the process of making a nanocomposite, as it will help to disperse the nanotubes uniformly, which will eventually create the superior properties of the resulting nanocomposite. In addition, among the currently available methods for functionalization, carboxylic-functionalization is the best for uniform dispersion. 

HuelsAG Methyl isobutyl ketone (MIBK) Acetone One-step condensation/hydrogenation process 2 1985... 

A very useful synthesis of 3(2H)-pyridazinones (18), comprising a multicomponent system, has been developed by Schmidt and Druey. Although the reaction can be performed as a one-step condensation between a 1,2-dicarbonyl compound, an ester with a reactive a-methylene group, and a monosubstituted or unsubstituted... 

The microwave-enhanced synthesis of symmetrical and asymmetrical bis(benzimidazol-2-yl)methanes 38 from appropriately substituted benzimidazole 2-acetic acid 36 and substituted-l,2-diaminobenzene 37 under solvent-free conditions without any catalyst has been performed in good yields (Scheme 10) [43]. The symmetrical bis(benzimidazol-2-yl)methanes 40 have similarly been prepared by one-step condensations of malon-... 

The best nitrogen-based ligand system to date for the rhodium-catalyzed hydrosilylation of 1-phenylethanone is the pyridinylthiazolidine system, e.g., methyl (4/ )-2-methyl-2-(2-pyridinyl)-4-thiazolidinecarboxylate (6) and ethyl (4/ )-2-(2-pyridinyl)-4-thiazolidinecarboxylate (7)11, where only a small ligand excess is needed. Ligands of the former type, accessible via a one-step condensation of 2-pyridinecarboxaldehyde and cysteine esters, are commercially available. 

ALAS (EC 2.3.1.37) uses PLP as a cofactor and catalyzes the one step condensation of glycine and succinyl-CoA to give rise to ALA, carbon dioxide, and free coenzyme A (Figure 3). ALAS belongs to the ct-oxoamine synthase subfamily of PLP-dependent enzymes that typically catalyze the condensation of a carboxylic acid coenzyme A thioester and an amino acid with the concomitant decarboxylation of the latter. Since the first description of ALAS activities in 1958 by Neuberger and coworkers and by Shemin and coworkers, ALAS... 

In 1995, Bolm et al. reported that the vanadium complexes of the triden-tate and amino-acid derived ligands 15 catalyze the enantioselective sulfoxidation of prochiral thioethers with dihydrogen peroxide as the terminal oxidant (Scheme 8) (24). The ligands are synthesized by a one-step condensation of the readily available salicylic aldehydes 16 with amino-acid derived amino alcohols, such as 17a. 

The 1,2,4,5-dithiadiazines 223 and 133 have been synthesized in good yield by a one-step condensation reaction of A -phenyl-A-chloroisothiocarbamoyl chloride with a range of thiosemicarbazide derivatives 222 (Equation 22) <2002IJH153, 2002ASJ162, 2005ASJ2800>. 

The solid-state reaction of ninhydrin with dimedone in a ball mill proceeds only as a one-step condensation to give 1 1 product 104 with 100% yield (Scheme 2.36) [27]. In solution, compound was previously obtained in 82% yield as aldol addition product. In solid-state conditions, product 104 was reluctant to eliminate water and form aldol product. Dehydratization was not observed even with gaseous trimethyl-amine, hydrogen chloride or p-toluenesulfonic acid, and this behavior is in contrast to typical condensation reactions of ninhydrin. 

Lamaty and collaborators have carried out solvent-free synthesis of nitrones in a ball mill [43]. Equimolar amounts of various aldehydes and A -substituted-hydrox-ylamines were used in conjunction with sodium bicarbonate (Scheme 3.64). For stoichiometric reaction between benzaldehyde and AT-methylhydroxylamine hydrochloride, small amount of dichloromethane was used. This reaction proceeded as a one-step condensation to give the corresponding nitrones in nearly quantitative yields, without the need to exclude air and moisture, in a shorter reaction time than by classical methods, but with comparable yields, where excess of reagents under inert atmosphere are reacted at room temperature or under heating for 1 or 2days (selected results. Table 3.32). Furthermore, the F,Z-isomeric ratio of the products obtained in ball-milling conditions were identical to those already reported in literature all the nitrones were in the more stable Z-form, with the exception of A -(naphth-2-ylmethylidene) methylamine A -oxide, known to be in the F-form. Microwave-assisted reactions gave lower yields than ball mill. 

Scheme 2. Cyclization reaction, possible reaction pathways A) one-step condensation building the eight-membered ring directly B) two-step condensation with chain prolongation and subsequent cyclization.

Scheme 2.90 One-step condensation of an alcohol with PCI3.

Type of reaction C-C bond formation Reaction conditions Solvent-free, room temperature Synthetic strategy One-step condensation Cataiyst Niobium pentachloride (NbCls)... 

Deanin and Dossi used the propylene oxide-MA reaction to prepare cured polyester resin products in a one-step procedure. In the method explored, the epoxide, MA, phthalic anhydride, styrene, lithium bromide, and benzoyl peroxide were combined, heated to a melt, and cured as castings. The properties of the cured materials were inferior to conventional systems. Others have also studied this concept.A one-step (condensation-addition) polymerization procedure has also been studied as a method for preparing coatings " and laminates with epoxy resins. 

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