Alkyl orthoformates are important intermediates for organic synthesis, widely used in medicines, pesticides and flavors. Alkyl orthoformates, in general, are transparent liquids that decompose in water and are soluble in methanol and chloroform.

US4141920A - Process for the preparation of trimethylsulfoxonium bromide - Google Patents

Alkyl orthoformates in acid media generate alkoxonium, which is a powerful electrophilic agent used as one carbon building block, and two alcohol molecules, which constitutes an important protecting groups. Alkyl orthoformates have also been reported as highly selective O, S and C-alkylating agents due to their ability to furnish methyl groups by releasing methyl formate, which is a good leaving group.

Thus, alkyl orthoformates are versatile chemical reagents, used to supply nucleophilic oxygen and eletrophilic carbon atoms. Recent applications of alkyl orthoformates are shown below. Year Archive Related E-Products. Download PDF. A Thiohydantoins and their derivatives represent an important class of biologically active molecules with many medicinal and agrochemical applications. Thiohydantoins underwent a one-pot chemoselective S-alkylation and acetylation by giant vac impeller orthoformate in the presence of ZnCl 2 and acetic anhydride.

The reaction furnished the desired S-alkylated products in moderate to good yields. D Recently, Yadav et al. E The reaction of aldehydes and ketones with trimethyl orthoformate is one route to obtain the protection of the carbonyl group. The water scavenger property of trimethyl orthoformate is explored in a high-pressure-promoted uncatalyzed acetalization of ketones. The acyclic and cyclic acetals were obtained in excellent yields. The N -acylthiazolidinethione moiety formed is cleaved to alcohol, ester or Weinreb amide, and the acetal can serve as an effective functional handle for numerous transformations.

G Periasamy et al. This one-pot procedure furnished 4-alkoxy-1,1,1-trihaloalkenones, an important building block in heterocyclic synthesis. A modified Mukaiyama aldol-Prins reaction involved cyclization of vinyl ethers with alkyl orthoformates using a Lewis acid. Overall, six new stereocenters were generated in this single reaction. B Trimethyl orthoformates have been used extensively in heterocyclic synthesis. C Recently, Beifuss et al.

I The Mukaiyama aldol-Prins reaction is an alternative tandem process in which an oxocarbenium generated from the Mukaiyama aldol addition undergoes an intramolecular Prins reaction to produce tetrahydropyrans.These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily.

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Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. Cite this: Ind. Article Views Altmetric. Citations Note: In lieu of an abstract, this is the article's first page.

Cited By. This article is cited by 58 publications. Subodh Kumar and Suman L. Oliver Kappe. Heldebrant and, Philip G. Journal of the American Chemical Society19 The Chemistry of Dimethyl Carbonate. Accounts of Chemical Research35 9 The Journal of Organic Chemistry63 25 Shaikh,Swaminathan Sivaram. Organic Carbonates. Chemical Reviews96 3 Catalytic reductive deoxygenation of esters to ethers driven by hydrosilane activation through non-covalent interactions with a fluorinated borate salt.

Continuous flow upgrading of glycerol toward oxiranes and active pharmaceutical ingredients thereof. Green Chemistry21 16 Cumming, Pablo Garcia-Losada. Scale-up of N -alkylation reaction using phase-transfer catalysis with integrated separation in flow. Efficient and selective microwave-assisted O-methylation of phenolic compounds using tetramethylammonium hydroxide TMAH.

Green Processing and Synthesis8 1 Catalysis Today, Tundo, M. Musolino, F.Green, P. BF 3 together with a dehydrating agent or other means of water removal that will drive the equilibrium in the following reaction to the right.

As an example of the use of a dehydrating agent, acetalization can be carried out by using methanol with trimethyl orthoformate or the orthoformate alone. Trimethyl orthoformate forms methyl formate and methanol on reaction with water and thus removes the water from the reaction mixture. Deprotection is often performed by acid-catalyzed transacetalization in acetone in excess or as solventor hydrolysis in wet solvents or in aqueous acid.

Acetals offer stability against all types of nucleophiles and bases and most oxidants, so long as the conditions do not lead to hydrolysis of the acetal. Hydride reductions in neutral and basic media will generally not affect acetal-protected carbonyls.

Up to now, various mild methods for acetalization and deacetalization have been developed to spare other acid-sensitive functionality, such as the use of catalysts such as ammonium nitrate, Amberlyst or silica gel, and dehydrating agents such as P 2 O 5. Perchloric acid adsorbed on silica gel is an extremely efficient, inexpensive, and reusable catalyst for the protection of aldehydes and ketones and the subsequent deprotection.

Acetalization was mostly carried out under solvent-free conditions with trialkyl orthoformates, but weakly electrophilic carbonyl compounds and substrates that can coordinate with the catalyst, required the corresponding alcohol as solvent. Kumar, D. Kumar, A. Chakraborti, Synthesis, Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide in absolute alcohol.

This convenient, mild, chemoselective method allows acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, and tolerates acid-sensitive protecting groups.

Gopinath, Sk. Haque, B. Patel, J.

trimethyl orthoformate as a highly selective mono

Pd catalysis enables a highly efficient and simple method for masking a broad range of carbonyl groups as acetals and ketals in excellent yields. This protocol is mild and proceeds with a very low catalyst loading at ambient temperature.

Mensah, S.Don't have a profile? View more versions of this product. Product Code. No offer available. View All Antibodies. Antibodies Advanced Search. Biochemicals and Reagents. Biological Buffers. Custom Services and Products. Enzymes and Inhibitors. View All Protein Biology. View All Life Sciences. Calibration Weights. Laboratory Balances. Weighing Papers and Dishes. Cell Culture Media.

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View All Cell Analysis. Custom Assays, Antibodies, Oligos. Centrifugal Filter Devices. Centrifuge Accessories. Centrifuge Adapters. Centrifuge Buckets.The present invention concerns an improved process for the preparation of trimethylsulfoxonium bromide.

Dimethyl acetals

The improvement in the process comprises the addition of a scavenger selected from the group consisting of trimethyl orthoformate, triethyl orthoformate and tetramethyl orthocarbonate to the reaction mixture of dimethylsulfoxide and methyl bromide. Trimethylsulfoxonium bromide is described by Blaschette and Buerger, Inorg. The reaction of alkyl halides with sulfoxide compounds is described in the article by Kuhn and Trischmann, Ann. More particularly, the article describes preparation of trimethylsulfoxonium iodide by heating for several days a mixture of dimethyl sulfoxide and methyl iodide.

No violent reaction has been reported in connection with this reaction.

Trimethyl orthoformate

Scaros and Joy A. Serauskas, Chem. News, 51 5137 and Chem. The hazards of the violent reaction and explosion have been attributed to the presence of bromine and hydrogen bromide as the by-products in the reaction mixture. These two ingredients appear to catalyze the rapid exothermic decomposition of the reaction mixture leading to the formation of gaseous products and the buildup of gas pressure which causes the reaction vessel to explode.

Because of inherent hazards the reaction of dimethylsulfoxide and methyl bromide is customarily carried out in a barricaded area equipped with the proper equipment to control any possible decomposition. The pressure is carefully monitored and plotted on a chart with respect to time; if a break in the normal pressure time curve occurs indicating a pressure buildup due to the gaseous decomposition products the reaction is stopped at once.

The hazards involved in this reaction may also be reduced by decreasing the reaction time to less than 50 hours. However, this may not be suitable because yields of trimethylsulfoxonium bromide will also be reduced.

It is an object of the present invention to avoid hazards described above and to provide simpler and safer procedure for the preparation of trimethylsulfoxonium bromide with little, if any, loss in the desired product. According to the present invention, the reaction of dimethylsulfoxide and methyl bromide is carried out in the presence of a scavenger such as trimethyl orthoformate, triethyl orthoformate and tetramethyl orthocarbonate.

It is believed that the scavenger reacts with the bromine and hydrogen bromide by-products and, thus, prevents the possible exothermic decomposition of the mixture. The role of trimethyl orthoformate as the scavenger can be shown by the following scheme. STR1 The effectiveness of the scavengers in keeping the quantity of bromine and hydrogen bromide low, the two ingredients which appear to catalyze the rapid decomposition of the reaction mixture is shown in Table 1, on the next page.

Tetramethyl orthocarbonate is the preferred scavenger. The most preferred scavenger is trimethyl orthoformate. The reaction temperature is not critical. The following Examples are given to further illustrate the present invention.

trimethyl orthoformate as a highly selective mono

They should not be construed as limiting the invention either in spirit or in scope. A 20 liter glass carboy is charged with 10 l. The carboy is stoppered and connected to a gas trap filled with dimethyl sulfoxide. The gas trap serves to relieve any pressure within the carboy and scrub any methyl bromide that escapes.

This mixture is left to react for about 28 days at room temperature. At the end of this time, crystals formed in the carboy. The crystals are removed by filtration, washed with 3 l. A mixture of 5 kg. The resulting warm solution is filtered through Celite brand of diatomaceous earth sold by Johns-Manville Corporation to remove Darco brand of activated carbon, grade G, sold by Chemical Division of Atlas Chemical Industries, Inc.

Then, 20 l. The white crystals of pure trimethylsulfoxonium bromide which formed are separated by filtration, washed with 5 l.

A 2-liter glass pressure vessel tested to psi is charged with ml. A thermo-watch is used to control temperature during this time. At the end of 55 hours heating is discontinued, the reaction bottle cooled to room temperature and vented through the vent valve.These metrics are regularly updated to reflect usage leading up to the last few days.

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Find more information on the Altmetric Attention Score and how the score is calculated. In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed. View Author Information. Marta, Venezia, Italy. Cite this: J. Article Views Altmetric. Citations Cited By. This article is cited by 14 publications. The Journal of Organic Chemistry84 15 ACS Catalysis7 2 Chemistry — A European Journal25 14 Angewandte Chemie36 Angewandte Chemie International Edition57 36 Larock, Tuanli Yao.

One-pot tandem cyclization of enantiopure asymmetric cis -2,5-disubstituted pyrrolidines: Facile access to chiral heteroazatriquinanes. Beilstein Journal of Organic Chemistry9 Organocatalyzed, enantioselective synthesis of bicyclo-[2. Tetrahedron66 26 A one-pot chemoselective S-alkylation and acetylation of thiohydantoins using the alkyl orthoformate—ZnCl2—Ac2O reagent system.

Tetrahedron Letters49 38 Indium trichloride promoted stereoselective synthesis of O-glycosides from trialkyl orthoformates. Tetrahedron Letters49 33 Taylor, Timothy Snowden. Triethyl Orthoformate.Don't have a profile? Highly flammable liquid and vapor. Remove contact lenses, if present and easy to do. Continue rinsing. WARNING: The information provided on this web site was developed in compliance with European Union EU regulations and is correct to the best of our knowledge, information and belief at the date of its publication.

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trimethyl orthoformate as a highly selective mono

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trimethyl orthoformate as a highly selective mono

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