Benign synthesis of unsymmetrical arylurea derivatives using 3-substituted dioxazolones as isocyanate surrogates

Chamni, Supakarn; Zhang, Jinquan; Zou, Haifeng

doi:10.1080/17518253.2020.1807616

Cited by 11 publications

(11 citation statements)

References 55 publications

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“…While isocyanates or isothiocyanates are generally toxic and potential irritants, , it should be recognized that the addition of HP(O)Ph 2 to isocyanates or isothiocyanates is the most atom efficient methodology for the synthesis of phosphinylcarboxamides or phosphinylthiocarboxamides, avoiding the use of stoichiometric reagents or low atom economic processes. , Isocyanates can be generated in situ , − but this uses additional stoichiometric reagents or metal catalysts to activate the isocyanate precursors. It is worth noting that the majority of organophosphorus P(V) derivatives are originally derived from toxic and pyrophoric white phosphorus.…”

Section: Resultsmentioning

confidence: 99%

Catalyst-free Hydrophosphinylation of Isocyanates and Isothiocyanates under Low-Added-Solvent Conditions

Huke

Taylor

Argent

et al. 2021

ACS Sustainable Chem. Eng.

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A catalyst-free, low-solvent method for the hydrophosphinylation of isocyanates and isothiocyanates is reported. A range of phosphorus nucleophiles including secondary phosphine oxides HP(O)R 2 (R = Ph, i Pr), phosphites HP(O)(OR) 2 (R = Me, Et), and methyl phenylphosphinate were tested. The procedure tolerated isocyanates and isothiocyanates featuring a wide range of substituents and, with use of 4 equiv of 2-methyltetrahydrofuran (2-MeTHF), solid substrates can be utilized. Twenty-five compounds were prepared with improved functional group tolerance compared to previous methods allowing access to new compounds (16 are novel). Facile scale up and simple reaction conditions make this a straightforward and practical methodology for obtaining phosphorus analogues of ureas and thioureas, which are challenging to synthesize by other methods.

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Section: Resultsmentioning

confidence: 99%

Catalyst-free Hydrophosphinylation of Isocyanates and Isothiocyanates under Low-Added-Solvent Conditions

Huke

Taylor

Argent

et al. 2021

ACS Sustainable Chem. Eng.

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“…White solid; yield: 0.260 g (86%); R f = 0.5 (20% EtOAc/n-hexane); mp 182-183 °C. 33 White solid; yield: 0.216 g (83%); R f = 0.5 (20% EtOAc/n-hexane); mp 171-173 °C.…”

Section: -(2-iodophenyl)-3-phenylurea (3d) 31mentioning

confidence: 99%

“…White crystals; yield: 0.162 g (85%); R f = 0.35 (20% EtOAc/n-hexane); mp 144-148 °C. 33 White crystals; yield: 0.152 g (79%); R f = 0.5 (20% EtOAc/n-hexane); mp 171-173 °C. 35 White crystals; yield: 0.145 g (76%); R f = 0.5 (20% EtOAc/n-hexane); mp 176-177 °C.…”

Section: -(2-methoxyphenyl)-3-phenylurea (3h) 16bmentioning

confidence: 99%

“…NMR (125 MHz, DMSO-d 6 ):  = 152.3, 139.8, 139.5, 138.9, 128.8, 128.5, 125.0, 123.0, 121.9, 118.1, 91.3.1-(2-Bromophenyl)-3-phenylurea (3e)33 White solid; yield: 0.216 g (83%); R f = 0.5 (20% EtOAc/n-hexane); mp 171-173 °C.1 H NMR (500 MHz, DMSO-d 6 ):  = 9.44 (s, 1 H), 8.11 (s, 1 H), 8.06-8.04 (m, 1 H), 7.61-7.59 (m, 1 H), 7.45 (d, J = 7.5 Hz, 2 H), 7.34-7.27 (m, 3 H), 6.99-6.94 (m, 2 H). 13 C NMR (125 MHz, DMSO-d 6 ):  = 152.1, 139.4, 137.0, 132.4, 128.8, 128.0, 124.0, 122.2, 122.1, 118.2, 113.0.…”

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confidence: 99%

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N-Acylbenzotriazoles as Proficient Substrates for an Easy Access to Ureas, Acylureas, Carbamates, and Thiocarbamates via Curtius Rearrangement Using Diphenylphosphoryl Azide (DPPA) as Azide Donor

Yadav¹,

Singh²,

Agrahari³

et al. 2021

Synthesis

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A diverse range of urea, N-acyl urea, and thiocarbamates has been synthesized in good to excellent yields by reacting N-acylbenzotriazoles individually with amines or amides or thiols or phenols in presence of diphenylphosphorylazide (DPPA) as a suitable azide donor in anhydrous toluene at 110 oC for 3-4 hours. In this route, DPPA is found to be a well alternative of trimethylsilylazide and NaN3 for the azide donor in Curtius degradation. The high reaction yields, one-pot and metal-free condition, straight-forward nature, easy to handling, use of readily available reagents, and in many cases avoid of the column chromatography are the notable features of the devised protocol.

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“…The reaction was typically carried out at high processing temperatures (>120 °C) by reacting high-molecular-weight diamines or alkanolamines with urea in bulk or in solution [ 50 , 51 , 52 , 53 , 54 , 55 ]. These high-temperature processes are still used in industry for making products such as phenylureas [ 3 , 4 , 56 , 57 , 58 , 59 , 60 , 61 ] used as herbicides and coatings [ 61 , 62 , 63 ], polyalkylenureas used for melamine-formaldehyde modification [ 64 ] and cycloalkyleneureas produced from 1,2-ethylenediamine or 1,3-propylenediamine and used for easy-care cellulose-containing textiles [ 64 , 65 ]. Recently, ureido functionalization of chitosan, in a low-temperature aqueous process, has enabled the synthesis of high-quality chitosan aerogels [ 47 , 66 ].…”

Section: Introductionmentioning

confidence: 99%

Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Guerrero‐Alburquerque

Zhao

Rentsch

et al. 2021

Polymers

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Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

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Benign synthesis of unsymmetrical arylurea derivatives using 3-substituted dioxazolones as isocyanate surrogates

Cited by 11 publications

References 55 publications

Catalyst-free Hydrophosphinylation of Isocyanates and Isothiocyanates under Low-Added-Solvent Conditions

Catalyst-free Hydrophosphinylation of Isocyanates and Isothiocyanates under Low-Added-Solvent Conditions

N-Acylbenzotriazoles as Proficient Substrates for an Easy Access to Ureas, Acylureas, Carbamates, and Thiocarbamates via Curtius Rearrangement Using Diphenylphosphoryl Azide (DPPA) as Azide Donor

Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

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