121693-37-6Relevant articles and documents
Methylation of Polyols with Trimethylphosphate in the Presence of a Lewis or Br?nsted Acid Catalyst
Duclos, Marie-Christine,Herbinski, Aurélien,Mora, Anne-Sophie,Métay, Estelle,Lemaire, Marc
, p. 547 - 551 (2018)
The alkylation of alcohols and polyols has been investigated with alkylphosphates in the presence of a Lewis or Br?nsted acid catalyst. The permethylation of polyols was developed under solvent-free conditions at 100 °C with either iron triflate or Aquivion PW98, affording the isolated products in yields between 52 and 95 %. The methodology was also adjusted to carry out peralkylation with longer alkyl chains.
Selective radical-chain epimerisation at C-H centres α to oxygen under conditions of polarity-reversal catalysis
Dang, Hai-Shan,Roberts, Brian P.
, p. 4271 - 4274 (1999)
Polarity-reversal catalysis by tri-tert-butoxysilanethiol has been applied to promote radical-chain epimerisation selectively at carbon centres of the type R1R2C*(H)OR.
Dimethyl isosorbideviaorganocatalystN-methyl pyrrolidine: scaling up, purification and concurrent reaction pathways
Annatelli, Mattia,Aricò, Fabio,Dalla Torre, Davide,Musolino, Manuele
, p. 3411 - 3421 (2021/06/06)
Dimethyl isosorbide (DMI) is a well-known bio-based green replacement for conventional dipolar solvents such as dimethyl sulfoxide and dimethylformamide. The synthesis of DMI mainly relies on the etherification of the bio-based platform chemical isosorbide in the presence of basic or acid catalysts and by employing different alkylating agents. Among them, dimethyl carbonate (DMC) is considered one of the most promising for its good biodegradability and low toxicity. In this work, we report on a comprehensive investigation on high yielding methylation of isosorbideviaDMC chemistry promoted by nitrogen organocatalystN-methyl pyrrolidine (NMPy). Reaction conditions were optimized and then efficiently applied for the methylation of isosorbide epimers, isoidide and isomannide, and for some preliminary scale-up tests (up to 10 grams of isosorbide). The purification of DMI from the reaction mixture was achieved by both column chromatography and distillation at reduced pressure. NMPy demonstrated to be an excellent catalyst also for the one-pot conversion ofd-sorbitol into DMI. Furthermore, for the first time, all seven methyl and methoxycarbonyl intermediates observed in the etherification of isosorbide were synthetised, isolated and fully characterised. This has provided an insight on the concurrent reaction pathways leading to DMI and on the role played by NMPy in the methylation of isosorbide. Finally, the reaction mechanisms for the methylation, methoxycarbonylation and decarboxylation promoted by NMPy partaking in the conversion of isosorbide into DMIviaDMC chemistry have been proposed.
Catalytic etherification of hydroxyl compounds to methyl ethers with 1,2-dimethoxyethane
Che, Penghua,Lu, Fang,Si, Xiaoqin,Xu, Jie
, p. 24139 - 24143 (2015/03/18)
1,2-Dimethoxyethane is explored for the first time as etherification agent for the acid-catalyzed synthesis of methyl ethers from biomass-derived hydroxyl compounds. H3PW12O40 catalyst can provide the formation of isosorbi
Selective radical-chain epimerisation at electron-rich chiral tertiary C-H centres using thiols as protic polarity-reversal catalysts
Dang,Roberts,Tocher
, p. 2452 - 2461 (2007/10/03)
Radical-chain epimerisation at chiral tertiary CH centres adjacent to ethereal oxygen atoms can be brought about in the presence of thiols, the function of which is to act as protic polarity-reversal catalysts for hydrogen-atom transfer between pairs of nucleophilic α-alkoxyalkyl radicals. The viability of the method is demonstrated by epimerisation of a series of simple molecules that contain two chiral centres and then the procedure is applied to more complex carbohydrate-based systems, where it is possible to convert a readily available diastereoisomer into a rarer one in a straightforward manner. Of necessity, epimerisation always proceeds in the direction of thermodynamic equilibrium and, in general, the results obtained are in accord with the predictions of molecular mechanics calculations using the MMX force-field. When the required isomer is less stable than the starting diastereoisomer, thiol-catalysed epimerisation of a suitable derivative of the parent can provide a means to obtain the desired compound in satisfactory yield, after deprotection of the epimerised derivative. This strategy is demonstrated for the conversion of trans-cyclohexane-1,2-diol into the less stable cis-isomer and for related contra-thermodynamic isomerisation of some carbohydrates, as well as for the conversion of meso-1,2-diphenylethane-1,2-diol into the dl-form. Thiol-catalysed epimerisation at a CH centre adjacent to an ether-oxygen atom is much faster than at a similar centre adjacent to an amido-nitrogen atom, a result that can be understood in terms of the importance of polar effects on the rate of abstraction of hydrogen by electrophilic thiyl radicals.
