One-step conversion

In the three-step process acetone first undergoes a Uquid-phase alkah-cataly2ed condensation to form diacetone alcohol. Many alkaU metal oxides, metal hydroxides (eg, sodium, barium, potassium, magnesium, and lanthanium), and anion-exchange resins are described in the Uterature as suitable catalysts. The selectivity to diacetone alcohol is typicaUy 90—95 wt % (64). In the second step diacetone alcohol is dehydrated to mesityl oxide over an acid catalyst such as phosphoric or sulfuric acid. The reaction takes place at 95—130°C and selectivity to mesityl oxide is 80—85 wt % (64). A one-step conversion of acetone to mesityl oxide is also possible. 

C=N, C=S, C=C, and N N containing substrates. Thus oxa2oles, imidazoles, thiazoles, p rrroles, and 1,2,4-triazoles have been prepared, respectively. Furthermore, p-tolylsulfonylmethyl isocyanide has found use in a one-step conversion of ketones into cyan-idea and in a two-step synthesis of a-hydroxyaldehydes from ketones. ... 

The availability of large and fast computers, in combination with numerical techniques to compute transient, turbulent flow, has made it possible to simulate the process of turbulent, premixed combustion in a gas explosion in more detail. Hjertager (1982) was the first to develop a code for the computation of transient, compressible, turbulent, reactive flow. Its basic concept can be described as follows A gas explosion is a reactive fluid which expands under the influence of energy addition. Energy is supplied by combustion, which is modeled as a one-step conversion process of reactants into combustion products. The conversion (combustion)... 

Although we treat this reaction as a simple, one-step conversion of A to P, it more likely occurs through a sequence of elementary reactions, each of which is a simple molecular process, as in... 

It is important to note that the one-step conversion of 27 to 28 (Scheme 4) not only facilitates purification, but also allows differentiation of the two carbonyl groups. After hydrogenolysis of the iV-benzyl group (see 28—>29), solvolysis of the -lactone-ring in 29 with benzyl alcohol and a catalytic amount of acetic acid at 70 °C provides a 3 1 equilibrium mixture of acyclic ester 30 and starting lactone 29. Compound 30 can be obtained in pure form simply by washing the solid mixture with isopropanol the material in the filtrate can be resubjected to the solvolysis reaction. 

A closely related procedure for preparing thietane dioxides is the one-step conversion of cyclic a-amino ketoximes (222) to 2-(co-cyanoalkyl)-3-dialkylaminothietane dioxides (226), with trans-orientation of the substituents249 (equation 86). 

Rosenau, T. Mereiter, K. Jager, C. Schmid, P Kosma, P. Sulfonium ylides derived from 2-hydroxy-benzoquinones crystal and molecular structure and their one-step conversion into Mannich bases by amine A-oxides. Tetrahedron 2004, 60(27), 5719-5723. 

Scheme 59. One-step conversion of indenobenzazepines to spirobenzylisoquinolines. Reagents a, (CF3C0)20, py b, aq NH3 c, NaBH4. 

Scheme 80. One-step conversion of 13-oxoallocryptopine (402) to indenobenzazepines. Reagents a, hv, /-BuOK, f-BuOH.

In 1979, Olah [47] reported a one step conversion of alicyclic ketones into lactams by means of hydroxylamine O-sulfonic acid and formic acid under reflux for a few hours. More recently this reaction has been realized under solvent-free conditions with Si02 as inorganic support and focused irradiation, as exemplified in Scheme 8.29 for caprolactam synthesis. 

This procedure constitutes the first example of one-step conversion of a /-alkane to the corresponding /-alkyfamine. Other hydrocarbons in this class, such as isobutane, have also been aminated with good results.7 Only a very limited number of convenient routes, e.g., the Ritter reaction, are available for the preparation of /-carbinamines. The present preparation illustrates a simple method that utilizes a novel substrate. 

Carlstrom and Frejd described the one-step conversion of o-diiodobenzene (or iodobenzene) with N-Boc dehydroalanine methyl ester to give vV-Boc-2-carbobenzyloxyindole in 30% yield [384],... 

MIBK is more complicated than the one-step conversion process for acetone and MEK. Manufacture of MIBK takes the three-step process shown in Figure 17—3, starting with acetone. 

This process (also known as the Ferrier II Reaction ) has proved to be of considerable value for the efficient, one-step conversion of 5,6-unsaturated hexopyranose derivatives into functionalized cyclohexanones useful for the preparation of such enantiomerically pure compounds as inositols and their amino, deoxy, unsaturated and selectively O-substituted derivatives, notably phosphate esters. In addition, the products of the carbocyclization have been incorporated into many complex compounds of interest in biological and medicinal chemistry. ... 

In 2000, Reddy and colleagues developed a one-step conversion of carboxylic acid to hydroxamic acid under neutral pH conditions using ethyl chloroformate as an activating reagent (Scheme 50). 

Araki et al. have found that La wesson s reagent, 2,4-bis(4-methoxyphenyl)-l,3-dithiaphos-phetane-2,4-disulflde, provides a convenient one-step conversion of mesoionic olates to mesoionic thiolates <88BCJ2977>. Thus 3-phenyl-1,2,3,4-thiatriazolium-5-olate (170) was converted to (171) in high yield by refluxing for 50 min in benzene (Equation (14)). This eompound had previously been prepared from compound (161 R = Ph) by treatment with sodium sulfide in aqueous dimethyl-formamide at room temperature <79JCS(Pi)732>. 

Isatoic anhydride undergoes a one-step conversion to o-aminophenyloxazolines 2 with amino alcohols via elimination of carbon dioxide. The reaction is carried out in the presence of kaolinitic clay in refluxing chlorobenzene. These o-aminophenyloxazolines, in particular, those derived from chiral amino alcohols,... 

The overall yield in the three-carbon chain extension of 2 to 6 is 37%. However, chain extension of 4 in the usual way failed, and only a 36% yield was obtained in the one-step conversion of 6 to 7. Further conversion of 7 to L-ribose is straightforward and essentially quantitative. 

Ethyl 5-bromopentanoxycarbamate (306), prepared by the reaction of (304) and (305), has been cyclized as a dilute solution of its potassium salt in DMF to give (307), which on subsequent hydrolysis gave (308). The direct one-step conversion of (304) and (305) to (308) was not successful (69JHC111). The same principle has been applied to the synthesis of the 2,3- and 3,2-benzoxazepines (71JHC911). 

Table 3. 2,2-Disubstituted Cyclopentane-1,3-diones by the One-Step Conversion of 1,2-Bis-(trimethylsiloxy)cyclobutcnc with Acetals3...

Apparently the only previous case of the isolation of a chlorinated acid from a haloform reaction is that reported by Arnold et al. [8], who acidified the reaction mixture before decomposition of the excess hypochlorite. (Even though we decomposed the excess hypochlorite before acidification, the unchlorinated acid was not obtained.) These authors [8] also obtained an ester as the product of the haloform reaction. It seems likely that conditions for performing the haloform reaction can be found which will make the one-step conversion of a methyl ketone to the ester of the corresponding acid a general reaction. ... 

Chemical synthesis of D-apiose has been accomplished by a number of methods.18,20,63 A one-step conversion of the branched-chain pentose 4-C-(hydroxymethyl)-D-threo-pentose (9) yielded18... 

B. Classon, Z. Liu, and B. Samuelsson, New halogenation reagent systems useful for the mild one-step conversion of alcohols into iodides or bromides, J. Org. Chem. 53 6126 (1988). 

A particularly convenient one-step conversion of carboxylic acids into dithioesters [140, 141] makes use of Davy s reagents [142], in which the R2S —P(=S) structural feature permits the two necessary functional group modifications, first OH substitution by SR2, followed by thionation of the C=0 group. 

Winterfeldt and Erning achieved the one-step conversion of 176 into the indolizidine 177 by a dissolving-metal reduction in the presence of diethyl oxalate.236 Treatment of the piperidine analog with sodium ethoxide and diethyl oxalate gave 10% of the dimer 178. 

Fused ring 7-lactones may also be formed by cyclizations of l-cycloalkeneacetic acids under equilibrating conditions. Nicolaou obtained evidence for the presence of an unstable -lactone in the phenyl-selenolactonization of 1-cyclohexeneacetic acid, but rearrangement occured readily at room temperature to the more stable 7-lactone (equation 12).32 An example of a one-step conversion of a 2-methyl-1-cyclohexeneacetic acid to a fused butenolide by use of diphenyldiselenide and electrochemical oxidation has been reported.47 Recent studies by Rutledge showed that simultaneous addition of bromine and thallium carbonate to 1-cyclohexeneacetic acid gave the 7-lactone as the exclusive product (compare to Table 2) however, the mechanism of this reaction may differ from other cyclofunctionalizations.21... 

A convenient one-step conversion of moderately activated nitroarenes to phenols was achieved in DMSO via nucleophilic nitrite displacement by the anion of an aldoxime.153 TTie resulting O-arylaldox-ime is rapidly cleaved to the phenol derivative under the reaction conditions. The reaction is also applicable to activated fluorides and even to 2-chloropyridine which, at 110 °C, is converted to 2-pyridone in 72% yield.153 A somewhat related process concerns the synthesis, in 82-92% yield, of 4-alkoxybenzoni-triles (45 R = Me, CH2-oxirane, CHrfh, CHMeCTfcMe from O-alkyl-4-nitrobenzaldoximes (44) via hydride-induced elimination of the alkoxide followed by alkoxy denitration (Scheme 17).154... 

E. J. Corey and B. Samuelsson, One-step conversion of primary alcohols in the carbohydrate series to the corresponding carboxylic tert-butyl esters, J. Org. Chem., 49 (1984) 4735. 

More often, carbamates of dextran are prepared by one-step conversion of the polysaccharide with isocyanates or isothiocyanates. This path is especially useful for the conjugation of fluorescent dyes. Fluorescent-marked dextrans are commercial products today. Fluorescent dextran derivatives with different molecular weights and substituents are available as invaluable tracers for studies on microcirculation and vascular permeability in health and disease [8]. Fluorescein isothiocyanate (FITC) dextran (actually the thiocarba-mate) has been well established in this area of research since the 1970s [358]. The isothiocyanate of fluorescein is covalently bound to dextran leading to... 

Aryl azides (such as 13) can be easily prepared from their corresponding amines (12) in one or two steps. Three examples are given in Scheme 2a. The most common method is the diazotization of the amine with sodium nitrite under acidic conditions (giving diazonium species 14), followed by addition of sodium azide in an aqueous medium (route i in Scheme 2a) [44], In 2003, the synthetic method was improved by application of triflyl azide (TfN3), which allowed a one-step conversion and gave improved yields (route ii in Scheme 2a) [45]. Recently, the development of sulfonyl azides 15 (with R = imidazole [46] or R = benzotriazole [47]) was reported these proved to be more stable reagents and allowed a conversion under mild conditions (route iii in Scheme 2a). 

Curtius degradation represents an interesting method for their one-step conversion into enan-tiomerically pure amines of the structure R RkTH—NH2. 

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