2749-70-4

The acid-catalyzed transacetalation of formaldehyde acetals (formal metathesis) is a suitable reaction for the generation of well-behaved Dynamic Libraries of cyclophane formals. The composition of the equilibrated mixtures solely depends on concentration

Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.

Dialkoxymethanes are becoming increasingly important as fuel additives, formaldehyde surrogates, and chemical intermediates, but the effective synthesis remains challenging. Herein, the catalytic synthesis of dialkoxymethane products using a molecular catalyst is reported. The catalytic system, comprising the [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3, enables the direct synthesis of dialkoxymethane products with formic acid as C1 building block in high to excellent turnover numbers.

The invention relates to a novel synthesis method of an alkoxymethylamine compound. The novel synthesis method comprises the steps: (1) dehydrating formaldehyde HCHO and alcohol R1OH by carrying out an aldolization under the action of an acid catalyst to obtain dialkoxymethane; and (2) carrying out a hydrocarbylation reaction on dialkoxymethane obtained in step (1) and substituted amine R2-NH2 toremove alcohol to obtain an alkoxymethyl substituent amine compound N-R1 oxymethyl-N-R2 amine. The synthesis method disclosed by the invention is simple in operation and high in yield reaching 92% orabove; and compared with the prior art, the novel synthesis method has the advantages that no acid wastewater, waste salts and chloromethyl alkyl ether serving as a cancerogen are greatly generated, the environment protection cost is favorably reduced, and the industrial prospect is higher.

221A simple and efficient method for the preparation of dialkoxymethane ethers (oxymethylene ethers) from alcohols and paraformaldehyde in the presence of commercially available nickel(II) salt is described. The reaction proceeds readily under neutral, solvent-free conditions using paraformaldehyde as a C 1 source. The present strategy has a broad substrate scope including aliphatic (both primary and secondary) and aromatic alcohols and provides a benign method for the preparation of symmetrical dialkoxymethanes in good yields (up to 89%). Graphical Abstract: SYNOPSIS A facile nickel-catalyzed synthesis of dialkoxymethane ethers from alcohols and paraformaldehyde using inexpensive, commercially available NiBr 2 is reported. The reaction proceeds readily under mild, neutral and solvent-free conditions. [Figure not available: see fulltext.].

The synthesis of dimethoxymethane (DMM) by a multistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3resulted in a versatile catalytic system for the synthesis of various dialkoxymethane ethers. This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into a formaldehyde oxidation level, thus opening access to new molecular structures using this important C1source.

Ring around the roses: The ipso substitution of benzene rings makes a simple and efficient synthesis of pillar[n]arenes (n=5, 6) possible. Pillar[6]arenes (see picture) and pillar[5]quinone, an oxidation product of pillar[5]arene, are novel highly promisi

A one pot synthesis of dialkoxymethanes (2a-h) is described from the reaction of alcohols (1a-h) with paraformaldehyde under reflux in the presence of catalytic amount of kaolinite.

A convenient and practical esterification was realized and this reaction proceeded without a dehydrating reagent or water removal equipment. The synthesis of esters by reaction of carboxylic acids with various alcohols such as methyl, ethyl, isopropyl, isobutyl, allyl, benzyl, propargyl and decanyl alcohols were achieved with a catalytic amount of CBr4 under refluxing reaction condition.

The reaction of various alcohols with paraformaldehyde in presence of montmorillonite to give dialkoxymethanes (2a-g) in very good yield is described.

The combined use of dimethoxymethane with catalytic amounts of tin(II) bromide and bromomethyl methyl ether cleaves p-methoxybenzyl ethers to give methoxymethyl ethers in good yields.The chemoselective conversion of p-methoxybenzyl ethers in the presence of the benzyl ether function into methoxymethyl ethers has also occurred successfully.

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Attempts to introduce new catalytic activities of potential use in synthetic transformations into enzyme active sites are described.Substitution of the naturally occurring zinc in carboxypeptidase A by several metals known to catalyse hydrogenation was investigated; a new protein characterised as a rhodium carboxypeptidase was isolated but it failed to show activity as a hydrogenation catalyst for the reduction of a series of dehydroamino acid amides.Horse liver alcohol dehydrogenase was investigated for its potential to act as an oxygen transferase via Lewis acid catalysis.A series of cyclohexenyl and phenylribosides together with new alkenyl(arenyl)oxymethylenoxyethanols was prepared for evaluation as substrates; in the course of this study, novel neighbouring group participation by the oxygen atom of a chloromethyl ether was observed.Although the binding of potential oxygen acceptors (alkenes and aromatic compounds) and oxygen donors (hydrogen peroxide and alkyl hydroperoxides) was demonstrated, oxygen transfer did not occur with the combinations investigated.In contrast to the failure of the above metalloenzymes to catalyse new reactions, papain modified at the active site sulfhydryl group by thiazolium salts and pyridinium salts was shown to exhibit reactions characteristic of the covalently attached cofactor.Thus the thiazolopapains acted as decarboxylation catalysts for pyruvate and the pyridinopapains could be reduced to dihydropyridines which reduced electrophilic carbonyl substrates with small enantiomeric excess.

With catalytic amounts of chlorotrimethylsilane/dimethyl sulphoxide (CTMSO/DMSO) in acetonitrile benzylic alcohols have been found to give high yields of styrenes.By using stoicheiometric amounts of reagents, different reaction pathways are observed: an elimination-addition sequence occurs with secondary and tertiary alcohols affording vicinal dichloro derivatives, β-chloro thioethers and allyl chlorides, whereas a nucleophilic substitution to the corresponding monochlorides occurs starting from primary and sterically hindered substrates.

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2-(Chloromethoxy)ethyl acetate reacts with alcohols in the presence of silver carbonate to produce 2-(alkoxymethoxy)ethyl acetates and bis(alkoxy)methanes.A mechanism which involves neighboring group participation of a chloromethyl ether oxygen atom is proposed to account for the formation of the latter products.

The influence of the nature of the catalyst on the reaction yields was studied in the synthesis of formaldehyde bis( beta -methoxyethyl) and dibenzyl acetals. The acetal yields were not greatly influenced by the nature of the catalyst. The synthesis was also effected in presence of polymeric ammonium salts. In comparison with earlier results, the polymeric salts in this case were more effective than their monomeric analogs.

The total synthesis of (+)-phyllanthocindiol starting with (S)-(+)-3-hydroxy-2-methylpropanoic acid and (S)-(-)-perilla aldehyde is reported.The totally enantioselective sequence elucidated the relative and absolute stereochemistry of (+)-phyllanthocindio

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