24318-47-6Relevant academic research and scientific papers
Systematic Evaluation of Sulfoxides as Catalysts in Nucleophilic Substitutions of Alcohols
Motsch, Sebastian,Schütz, Christian,Huy, Peter H.
supporting information, p. 4541 - 4547 (2018/09/13)
Herein, a method for the nucleophilic substitution (SN) of benzyl alcohols yielding chloro alkanes is introduced that relies on aromatic sulfoxides as Lewis base catalysts (down to 1.5 mol-%) and benzoyl chloride (BzCl) as reagent. A systematic screening of various sulfoxides and other sulfinyl containing Lewis bases afforded (2-methoxyphenyl)methyl sulfoxide as optimal catalyst. In contrast to reported formamide catalysts, sulfoxides also enable the application of plain acetyl chloride (AcCl) as reagent. In addition, it was demonstrated that weakly electrophilic carboxylic acid chlorides like BzCl promote Pummerer rearrangement of sulfoxides already at room temperature. This side-reaction also provided the explanation, why sulfoxide catalyzed SN-reactions of alcohols do not allow the effective production of aliphatic and electron deficient chloro alkanes. Comparison experiments provided further insight into the reaction mechanism.
Esterification of carboxylic acids with alkyl halides using imidazolium based dicationic ionic liquids containing bis-trifluoromethane sulfonimide anions at room temperature
Jadhav, Arvind H.,Lee, Kyuyoung,Koo, Sangho,Seo, Jeong Gil
, p. 26197 - 26208 (2015/10/20)
Task-specific room temperature ionic liquids (RTILs) composed of symmetrical N-methylimidazolium rings linked with a short oligo (ethylene glycol) chain (cationic part) and bis-trifluoromethane sulfonimide (NTf2, anionic part) were successfully synthesized, and their physicochemical properties were determined by various modern analytical techniques. The catalytic activity of the synthesized RTILs was evaluated in the esterification reaction of acids with alkyl halides in solvent-free conditions at room temperature. From the screening test, all the synthesized RTILs showed a high yield with significant selectivity for respective esters in a very short reaction time. Especially, 0.1 equimolar of RTIL-1 ([tetraEG(mim)2][NTf2]2) was found to be, the most efficient and reusable catalyst for this reaction. As a result, 100% conversion and up to a 94% yield of the respective ester product was obtained in a 30 min reaction time. This might be due to their synergetic effect of Lewis acidity, wide liquid range, and high miscibility compared to the other homogeneous and heterogeneous catalysts. Beside this, RTIL was easily separated from the reaction mixture and reused several times without any significant loss of catalytic activity and structural property. The present dicationic ionic liquids (ILs) under a solvent-free catalytic system were found to be kinetically fast, naturally benign, and achieved good yields for esterification of carboxylic acids with alkyl halides.
Bu4NI-catalyzed benzylic acyloxylation of alkylarenes with aromatic aldehydes
Huang, Juan,Li, Lan-Tao,Li, Hong-Ying,Husan, Ezizjan,Wang, Peng,Wang, Bin
supporting information, p. 10204 - 10206,3 (2020/08/24)
An nBu4NI-catalyzed benzylic C-H acyloxylation of alkylarenes with readily available aromatic aldehydes has been developed. These reactions occur under mild and clean reaction conditions using tert-butyl hydroperoxide as the green terminal oxid
Acyl Transfer as a Problematic Side Reaction in Polymer-Supported Oligosaccharide Synthesis
Nukada, Tomoo,Berces, Attila,Whitfield, Dennis M.
, p. 9030 - 9045 (2007/10/03)
Under a wide variety of glycosylation conditions acyl transfer to the polymer support competed with glycoside formation, including the pivaloyl protecting group. As well as acyl transfer, many glycosylations also led to the formation of polymer-bound β-1,2-linked oligomers of the donor. Using ethyl 2,6-di-O-pivaloyl-3,4-O-isopropylidene-β-D-galactothiopyranoside as donor under promotion of N-iodosuccinimide/silver trifluoromethanesulfonate in the presence of 2-methyl-2-butene, an 82% yield of glycoside was obtained along with pivaloylated polymer. Subsequent work showed that increasing the steric bulk about the alcoholic acceptor in conjunction with this 2-O-pivaloyl-protected glycosyl donor completely suppresses this side reaction, giving a nearly quantitative yield of glycoside. This contraintuitive approach of decreasing the reactivity of both the donor and the acceptor to minimize a side reaction is rationalized by assuming that the barrier to acyl transfer is more sensitive to the protecting groups than that of glycosylation. These developments led to a polymer-supported synthesis of the branch point trisaccharide of the group B type 1A Streptococcus capsular polysaccharide.
