- Microwave-assisted ionic liquid-catalyzed selective monoesterification of alkylphosphonic acids—an experimental and a theoretical study
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It is well-known that the P-acids including phosphonic acids resist undergoing direct es-terification. However, it was found that a series of alkylphoshonic acids could be involved in mo-noesterification with C2–C4 alcohols under microwave (MW) irradiation in the presence of [bmim][BF4] as an additive. The selectivity amounted to 80–98%, while the isolated yields fell in the range of 61–79%. The method developed is a green method for P-acid esterification. DFT calculations at the M062X/6–311+G (d,p) level of theory (performed considering the solvent effect of the corresponding alcohol) explored the three-step mechanism, and justified a higher enthalpy of activation (160.6–194.1 kJ·mol–1) that may be overcome only by MW irradiation. The major role of the [bmim][BF4] additive is to increase the absorption of MW energy. The specific chemical role of the [BF4] anion of the ionic liquid in an alternative mechanism was also raised by the computations.
- ábrányi-Balogh, Péter,Drahos, László,Harsági, Nikoletta,Henyecz, Réka,Keglevich, Gy?rgy
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- Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
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Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
- Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7683 - 7689
(2020/04/22)
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- Solvent-Free Michaelis-Arbuzov Rearrangement under Flow Conditions
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The first solvent- and catalyst-free procedure for the Michaelis-Arbuzov reaction under flow conditions was developed. A variety of alkylphosphonic esters could be obtained using this protocol starting from the corresponding trialkyl phosphites and even catalytic amounts of alkyl halides with very short reaction times (8.33-50 min) and excellent conversions. In general, this protocol works effectively when the alkyl halide is used in catalytic amounts as low as 5-10% only if it concerns the synthesis of homo alkylphosphonates. One equivalent and an excess of alkyl halides should be used in the reaction with alkyl phosphite if the alkyl group of the selected substrates differ. Thus, it provides a sustainable, fast alternative to the existing methods for the preparation of alkylphosphonates. The isolation of the reaction products is straightforward due to the lack of solvents and a high purity of the obtained products (conv ≥ 99%), and notably, in the catalytic procedures there are only traces of alkyl halides formed after the reaction is complete. The reactions conducted using a glass microreactor chip with an internal volume of 250 μL allow the production of 1.6-1.95 g of organophosphorus esters per hour.
- Jasiak, Aleksandra,Mielniczak, Grazyna,Owsianik, Krzysztof,Koprowski, Marek,Krasowska, Dorota,Drabowicz, Józef
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p. 2619 - 2625
(2019/02/26)
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- Fragmentation-Related Phosphonylation of Nucleophiles Utilizing P-Alkyl 2,3-oxaphosphabicyclo[2.2.2]octene 3-oxide Precursors
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New P-alkyl 2,3-oxaphosphabicyclo-[2.2.2]octene 3-oxides were synthesized by the Bayer-Villiger oxidation of the corresponding 7-phosphanorbornene 7-oxides and were used as precursors for reactive alkylmetaphosphonates useful in the phosphonylation of alcohols. This is the first case that the reactivity of the two regioisomers formed by O-insertion was differentiated and that the fragmentation-related phosphonylation leading to phosphonic acid-esters was achieved under microwave-assisted conditions.
- Kovács, Tamara,Fül?p, Laura Szandra,Keglevich, Gy?rgy
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- An optimized and scalable synthesis of propylphosphonic anhydride for general use
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Abstract Propylphosphonic anhydride (T3P) is an effective coupling and dehydrating agent, which has been used for a large number of chemical transformations. An efficient and versatile synthetic method is described to synthesize propylphosphonic anhydride (T3P) in pure form, in an overall yield of 51% in four steps from commercially available diethyl phosphonate.
- Pizova, Hana,Bobal, Pavel
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p. 2014 - 2017
(2015/03/30)
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- Amberlyst-15 catalyzed synthesis of alkyl/aryl/heterocyclic phosphonates
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A novel and efficient procedure for the synthesis of alkyl phosphonates through one pot condensation of alkyl halide and tri alkyl/aryl phosphite in the presence of amberlyst-15 as catalyst under solvent free conditions was applied. It demonstrated several advantages such as good yields of products, simple operation, convenient separation and inexpensive catalyst.
- Kunda, U.M. Rao,Mudumala, V.N. Reddy,Reddy Gangireddy,Nemallapudi,Sandip,Cirandur
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experimental part
p. 895 - 898
(2012/01/11)
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- Room-temperature alternative to the arbuzov reaction: The reductive deoxygenation of Acyl phosphonates
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The reductive deoxygenation of acyl phosphonates using a Wolff-Kishner-like sequence is described. This transformation allows direct access to alkyl phosphonates from acyl phosphonates at room temperature. The method can be combined with acyl phosphonate synthesis into a one pot, four-step procedure for the conversion of carboxylic acids into alkyl phosphonates. The methodology works well for a variety of aliphatic acids and shows a functional group tolerance similar to that of other hydrazone-forming reactions.
- Kedrowski, Sean M. A.,Dougherty, Dennis A.
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supporting information; experimental part
p. 3990 - 3993
(2010/11/02)
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- P-Toluenesulfonic acid-Celite as a reagent for synthesis of esters of alkylphosphonic acids under solvent-free conditions
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The coupling reaction of alkylphosphonic acids and alcohols on the surface of p-toluenesulfonic acid-Celite under mild and solvent-free conditions gave the corresponding phosphonates in excellent yields. This method provides a useful rapid synthesis of phosphonates for use in the unambiguous identification of chemical warfare agents.
- Gupta, Arvind K.,Kumar, Rajesh,Dubey, Devendra K.,Kaushik
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p. 328 - 331
(2008/02/10)
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- Direct aldehyde homologation utilized to construct a conjugated-tetraene hydrocarbon insect pheromone
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New phosphonate reagents were developed for the two-carbon homologation of aldehydes to methyl-or ethyl-branched unsaturated aldehydes and used in the practical synthesis of (2E,4E,6E,8E)-3,5-dimethyl-7-ethyl-2,4,6,8-undecatetraene (1), a pheromone of the beetle Carpophilus lugubris. The phosphonate reagents, diethyl ethylformyl-2-phosphonate dimethylhydrazone and diethyl 1-propylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condensation of the reagent with the starting aldehyde, followed by removal of the dimethylhydrazone protective group with a biphasic mixture of dilute HCl and petroleum ether. This robust two-step process replaces the standard three-step aldehyde homologation route using ester-based Horner-Wadsworth-Emmons reagents. The new synthesis of compound 1 from (2E)-2-methyl-2-butenal was run on a 10-g scale and required just five steps (two cycles of condensation and deprotection, followed by a final Wittig olefination) instead of the usual seven. In addition, the Wittig olefination step was simplified and its E-isomer selectivity was improved. The overall yield for the entire synthetic pathway was increased from 20% to 37%, enhancing the commercial potential of Carpophilus pheromones.
- Petroski, Richard J.,Bartelt, Robert J.
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p. 2282 - 2287
(2008/02/09)
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- An efficient method for the esterification of phosphonic and phosphoric acids using silica chloride
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Silica chloride is used as an effective heterogeneous catalyst for the rapid esterification of alkyl/aryl phosphonic/phosphoric acids to their corresponding alkyl/aryl phosphonates/phosphates under mild conditions with quantitative yields.
- Sathe, Manisha,Gupta, Arvind K.,Kaushik
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p. 3107 - 3109
(2007/10/03)
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- Surface-mediated solid phase reactions: A simple, efficient and base-free synthesis of phosphonates and phosphates on Al2O3
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Al2O3-supported solvent free condensation of alkylphosphonic dichlorides with alcohols at room temperature yielded phosphorus esters in excellent yields.
- Acharya, Jyotiranjan,Shakya, Purushottam D.,Pardasani, Deepak,Palit, Meehir,Dubey, Devendra K.,Gupta, Arvind K.
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p. 194 - 196
(2007/10/03)
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- Microwave irradiation in organophosphorus chemistry 1: The Michaelis-Arbuzov reaction
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A diverse series of phosphonate esters have been prepared using a domestic microwave oven. The microwave enhanced Michaelis-Arbuzov reaction shows remarkable rate acceleration under microwave irradiation and allows the facile synthesis, and in certain cases easy workup, of alkyl, α-substituted and aryl phosphonates.
- Kiddle, James J.,Gurley, Alison F.
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p. 195 - 205
(2007/10/03)
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- A new, effective approach for the C-C bond formation utilizing 1-, 2- and 3-phosphonyl substituted radicals derived from iodoalkylphosphonates and n-Bu3SnH/Et3B/O2 system
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A new, practical synthesis of highly substituted phosphonates utilizing 1-, 2- and 3-phosphonyl substituted radicals derived from iodoalkylphosphonates and a catalytic or stoichiometric amounts of the n-Bu3SnH/Et3B/O2 reagent is described.
- Balczewski,Pietrzykowski
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p. 7291 - 7304
(2007/10/03)
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- A free radical approach to functionalization of phosphonates utilizing novel 2- and 3-phosphonyl radicals
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A general method for the phosphonyl C2-C3-C bond formation under the free radical, reductive conditions is described. The new approach is based on the synthesis of novel 2- and 3-phosphonyl radicals 6, 9 derived from the corresponding 2- and 3-halo (X = Cl, Br, I) substituted phosphonates 7, 10 and their reaction with alkenes 4. Functionalized phosphonates 5, 8 possessing the 2+2 and 3+2 elongated carbon chain were obtained in 24-73% yields.
- Balczewski, Piotr,Pietrzykowski, Witold M.
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p. 13681 - 13694
(2007/10/03)
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- Conjugate addition of organocuprates to diethyl vinylphosphonate
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The reaction of organocuprate reagents with diethyl vinylphosphonate affords the conjugate addition product. The intermediate α-metalloalkylphosphonate can be quenched with electrophiles to afford α-substituted alkylphosphonates.
- Baldwin, I. Craig,Beckett, R. Paul,Williams, Jonathan M. J.
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- Phosphate-phosphonate conversion: a versatile route to linear or branched alkylphosphonates
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Addition of a symmetrically substituted trialkyl phosphate (R1O)3P(O) to a THF solution of an alkyllithium R2-CH2Li (2 equiv) at -78 deg C, followed by warming to room temperature, results in the quantitative formation of α-lithioalkylphosphonate.Treatment of the anion formed with aqueous HCl or an alkyl iodide yields the corresponding alkylphosphonate or α-substituted alkylphosphonate in good to excellent yields.Key Words: trialkyl phosphonates; alkyllithiums; α-lithioalkylphosphonates; alkylphosphonates.
- Patois, C.,Savignac, P.
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p. 630 - 635
(2007/10/02)
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- NEW SYNTHESIS OF DIETHYL ALKYLPHOSPHONATES AND DIETHYL ALKENYLPHOSPHONATES
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Organometallic reagents readily added to diethyl 1-(trimethylsilyl)vinylphosphonate 1 by virtue of the polarizing silyl group.Quenching with acetic acid, methyl iodide, and carbonyl compounds gave synthetically useful diethyl alkylphosphonates 6 and diethyl alkenylphosphonates 8 respectively.
- Chang, Kyeaongho,Ku, Bonchul,Oh, Dong Young
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p. 1891 - 1898
(2007/10/02)
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- CONVERSION DIRECTE PAR LES ALKYLLTHIENS DES PHOSPHATES EN PHOSPHONATES α-LITHIES
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Trialkylphosphates (RO)3P(O) can be converted into α-lithioalkanephosphonates by treatment with alkyllithiums (R1CH2Li) in two fold excess.
- Teulade, Marie-Paule,Savignac, Philippe
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p. 405 - 408
(2007/10/02)
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