New Synthesis of N-Acylurea Derivatives

Kutschy, Peter; Dzurilla, Milan; Ficeri, V.; Koščík, Dušan

doi:10.1135/cccc19930575

Cited by 14 publications

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“…To date N ‐acylureas are classically prepared by acylating ureas with suitably activated carboxylic acids such as acid chlorides, anhydrides and carbodiimides 6. The condensation of amines with acyl isocyanates7 or S ‐allyl N ‐acylmonothiocarbamates8 is also known to give N ‐acylureas. Other routes starting from ureas involve acylation with alkenyl esters9 and boronic acid‐catalysed condensation with acids 10.…”

Section: Methodsmentioning

confidence: 99%

Salt Rejection and Water Transport Through Boron Nitride Nanotubes

Hilder

Gordon

Chung

2009

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Nanotube-based water-purification devices have the potential to transform the field of desalination and demineralization through their ability to remove salts and heavy metals without significantly affecting the fast flow of water molecules. Boron nitride nanotubes have shown superior water flow properties compared to carbon nanotubes, and are thus expected to provide a more efficient water purification device. Using molecular dynamics simulations it is shown that a (5, 5) boron nitride nanotube embedded in a silicon nitride membrane can, in principle, obtain 100% salt rejection at concentrations as high as 1 M owing to a high energy barrier while still allowing water molecules to flow at a rate as high as 10.7 water molecules per nanosecond (or 0.9268 L m(-2) h(-1)). Furthermore, ions continue to be rejected under the influence of high hydrostatic pressures up to 612 MPa. When the nanotube radius is increased to 4.14 A the tube becomes cation-selective, and at 5.52 A the tube becomes anion-selective.

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Section: Methodsmentioning

confidence: 99%

Salt Rejection and Water Transport Through Boron Nitride Nanotubes

Hilder

Gordon

Chung

2009

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168

126

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“…Mono-and disubstituted acylureas 9 and 10 were obtained in good to excellent yields and high purities after TFA-mediated cleavage and column chromatography. These and following products of this study were characterized by 1 availability and instability 35 of acyl isocyanates constrained the diversity of the acyl residue within the target compounds and prompted us to modify the preparation of acylureas on solid support. Another approach for the synthesis of N-acyl-N 0 -alkylureas in solution comprises the reaction of monosubstituted ureas and carboxylic acids, anhydrides or chlorides.…”

Section: ' Results and Discussionmentioning

confidence: 99%

Solid-Phase Synthesis of Disubstituted N-Acylureas from Resin-Bound Ureas and Acyl Chlorides

et al. 2010

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Acylureas (ureides) are valued for their important biological activities. Whereas cyclic acylureas have frequently been the object of solid-phase chemistry, only few reports have focused on the solid-supported preparation of acyclic representatives. We have prepared different types of acylureas on Rink amide resin in three or four steps. The products are either N-acylated (9, 18), N-acylated-N'-alkylated (10, 19), or N-acylated-N-alkylated (22). Characteristic NMR parameters of isomeric acylureas 10, 19, and 22 are discussed.

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“…Whereas unsubstituted O-allyl N-acylmonothiocarbamates rearrange in boiling benzene during 9 -30 h (yield 50 -95%) 8,11 , the longest reaction time for O-substituted allyl N-acylmonothiocarbamates is 3 h (yield 45 -90%) under the same reaction conditions. According to reactivity in the [3,3]-sigmatropic rearrangement the O-substituted allyl esters 1 -20 can be divided into three groups: (i) stable (8,10,11,14,17,19) which are isolable as pure compounds and undergo [3,3]-sigmatropic rearrangement by heating in boiling benzene; (ii) moderately stable (1, 3 -5, 20) which can be isolated only as a mixtures with rearranged products and the [3,3]-sigmatropic rearrangement can be completed in boiling benzene; (iii) unstable (2, 6, 7, 9, 12, 13, 15, 16, 18) which can not be isolated because the reaction of acyl isothiocyanates with substituted allyl alcohols at room temperature affords dirrectly the products of [3,3]-sigmatropic rearrangement.…”

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confidence: 95%

[3,3]- Versus [1,3]-Sigmatropic Rearrangement of O-Substituted Allyl N-Acylmonothiocarbamates

Ficeri¹,

Kutschy²,

Dzurilla³

et al. 1994

Collect. Czech. Chem. Commun.

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Substituted allylic alcohols (2-buten-1-ol, 1-buten-3-ol, cinnamyl alcohol and 3-methyl-2-buten-1-ol) react with acyl isothiocyanates (4-chlorobenzoyl, 2,6-difluorobenzoyl, 3-phenylpropenoyl, 2-thienocarbonyl, 3-chloro-2-thienocarbonyl and 3-chloro-2-benzo[b]thienocarbonyl isothiocyanate) with the formation of highly reactive O-substituted allyl N-acylmonothiocarbamates, which either spontaneously or by heating in boiling benzene undergo [3,3]-sigmatropic rearrangement to S-substituted allyl N-acylmonothiocarbamates. The structure of S-esters with isomerized allylic group affords the unequivocal evidence of the [3,3]-sigmatropic route of studied rearrangement. Further heating of [3,3]-rearranged N-(4-chlorobenzoyl)monothiocarbamates results in the [1,3]-sigmatropic shift of monothiocarbamate group. Using arylalkyl alcohols with the allylic double bond inserted into an aromatic system the obtained O-esters either do not undergo any rearrangement (benzyl alcohol) or undergo [1,3]-sigmatropic rearrangement (2-and 3-furylmethanol and 1-(2-furyl)ethanol) to the corresponding S-esters. For explanation of this reaction the tandem of [3,3]-and [1,3]-sigmatropic rearrangements is suggested.The oxygen and sulfur containing 1,5-hexadiene systems of the type I (O-allyl monothioesters 1-4 , monothiocarbamates 5-8 , mono-3 and dithiocarbonates 6,9,10 ) are known to undergo a catalyzed or non-catalyzed [3,3]-sigmatropic rearrangement to compounds of the type II possessing the carbonyl and S-allyl instead of thiocarbonyl and O-allyl groups present in I. It was found 5,6 that substituents on allylic group, particularly α-methyl, accelerate the reaction I → II. Reactivity also depends on the nature of group R. O-Allyl monothioesters are less reactive than compounds with R bonded via heteroatom, e.g. O-allyl N,N-dialkylmonothiocarbamates. Reactivity of monothiocarbamates 2650 Ficeri, Kutschy, Dzurilla, Imrich:

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New Synthesis of N-Acylurea Derivatives

Cited by 14 publications

References 0 publications

Salt Rejection and Water Transport Through Boron Nitride Nanotubes

Salt Rejection and Water Transport Through Boron Nitride Nanotubes

Solid-Phase Synthesis of Disubstituted N-Acylureas from Resin-Bound Ureas and Acyl Chlorides

[3,3]- Versus [1,3]-Sigmatropic Rearrangement of O-Substituted Allyl N-Acylmonothiocarbamates

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