68750-24-3Relevant academic research and scientific papers
Expanding the scope of methyl xanthate esters - From Barton-McCombie reaction auxiliary to versatile protective group
Thorsheim, Karin,Manner, Sophie,Ellervik, Ulf
, p. 6329 - 6333 (2017/09/29)
The methyl xanthate ester is presented as a versatile protective group for alcohols. Hydroxyl groups can easily be transformed into methyl xanthate esters by several methods and are commonly used as an auxiliary in the Barton-McCombie reaction. We show that these methyl xanthate esters can readily and chemoselectively be cleaved under mild conditions by the action of diethylenetriamine using microwave heating. This method is orthogonal to many common hydroxyl protective groups that can be introduced and cleaved in the presence of methyl xanthate ester.
A lewis acid-promoted pinner reaction
Pfaff, Dominik,Nemecek, Gregor,Podlech, Joachim
supporting information, p. 1572 - 1577 (2013/10/22)
Carbonitriles and alcohols react in a Lewis acid-promoted Pinner reaction to carboxylic esters. Best results are obtained with two equivalents of trimethylsilyl triflate as Lewis acid. Good yields are achieved with primary alcohols and aliphatic or benzylic carbonitriles, but the straightforward synthesis of acrylates and benzoates starting with acrylonitrile and benzonitrile, respectively, is similarly possible. Phenols are not acylated under these reaction conditions. The method has been used for the first total synthesis of the natural product monaspilosin. In the reaction of benzyl alcohols variable amounts of amides are formed in a Ritter-type side reaction.
N,N-diarylammonium pyrosulfate as a highly effective reverse micelle-type catalyst for hydrolysis of esters
Koshikari, Yoshiki,Sakakura, Akira,Ishihara, Kazuaki
supporting information; experimental part, p. 3194 - 3197 (2012/07/31)
Reverse micelle-type N,N-diarylammonium pyrosulfate (3-5 mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for α-heterosubstituted carboxylic acids.
The trimethylsilyl xylyl (TIX) ether: A useful protecting group for alcohols
Reddy, Ch. Raji,Chittiboyina, Amar G.,Kache, Rajashaker,Jung, Jae-Chul,Watkins, E. Blake,Avery, Mitchell A.
, p. 1289 - 1295 (2007/10/03)
A new protecting group for alcohols, the p-trimethylsilyl xylyl (TIX) group has been developed. The TIX group is used to protect various alcohols under acidic as well as basic conditions. The protected ethers thus formed had noteworthy chemoselectivity upon deprotection in the presence of other benzyl ethers and commonly used protecting groups. The stability of the TIX group towards various reagents has also been examined.
Lipase-catalysed selective monoacylation of 1,n-diols with vinyl acetate
Framis, Victoria,Camps, Francisco,Clapés, Pere
, p. 5031 - 5033 (2007/10/03)
A simple enzymatic methodology for the selective monoacetylation of 1,n-diols (n=5,8) using vinyl acetate is reported. Monoacetylation excesses of 81-87% at 74-90% 1,n-diol conversions were obtained in toluene and diisopropyl ether using Thermomyces lanuginosus lipase (TLL) immobilised on polypropylene powder as catalyst.
Solid state acetylation with acetylimidazole: Selective protection of primary alcohols and phenols
Hagiwara, Hisahiro,Morohashi, Kimie,Suzuki, Toshio,Ando, Masayoshi,Yamamoto, Isao,Kato, Michiharu
, p. 2001 - 2006 (2007/10/03)
Primary alcohols and phenols have been acetylated with acetylimidazole by the solid state reaction, grinding both substrates with a pestle in a mortar.
Stepwise Approach toward First Generation Nonenzymatic Hydrolases
Madder, Annemieke,De Clercq, Pierre J.,Declercq, Jean-Paul
, p. 2548 - 2559 (2007/10/03)
The synthesis and reactivity study of a first generation serine protease mimic is described. Central in the design stands the possibility of stabilization of the transition state by an amino triol such as 8t. En route to 8t, a series of amino alcohols (4-8) was obtained, the reactivity of which was studied toward esterification by acetylimidazole (AcIm) and by p-nitro-2,2,2-trifluoroacetanilide (PNTFA). Interesting reactivity differences were observed between the cis- and the trans-series, especially between 7c and 7t (AcIm), and between 8c and 8t (PNTFA). In both cases the results are explained by invoking extra stabilization of the tetrahedral oxyanion.
Convenient Selective Monoacylation of 1,n-Diols Catalyzed by Ion-Exchange Resins
Nischiguchi, Takeshi,Fujisaki, Shizuo,Ishii, Yasuhiro,Yano, Yoshihiro,Nishida, Akiko
, p. 1191 - 1195 (2007/10/02)
Several 1,n-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were selectively monoacylated by transestrification in ester/octane solvent mixtures catalyzed by strongly acidic ion-exchange resisns.This method of selective esterification is quite simple and practical.The selectivity for monoester formation and initial rates of monoester formation depended on the ester/octane ratio of the solvents.The reasons for the selectivity are as follows: (1) The sulfonic acid-type ion-exchange resins usually contain 50-80percent water, and a strongly acidic aqueous layer is formed on the surface of the resins. (2) A partition equilibrium between the aqueous layer and the aprotic ester/octane layer is setup, and diols have higher partition coefficients than the product monoesters. (3) Acylation of the alcohols occurs in the aqueous layer and/or at the interface between the aqueous and the nonaqueous liquid layer. (4) The formed monoesters move away from the aqueous layer into the aprotic layer.
Unique Template Effects of Distannoxane Catalysts in Transesterification of Diol esters
Otera, Junzo,Dan-oh, Nobuhisa,Nozaki, Hitosi
, p. 3065 - 3074 (2007/10/02)
1,n-Diol diacetates (n = 2,3,4) are selectively converted into the corresponding monoacetates by distannoxane-catalyzed transesterification.Such unique selectivity is not encountered with 1,n-diol diacetates where n>/=5.A great difference in reactivity is also seen in the transesterification between methyl butyrate and 1,n-diol monoacetates: the ethylene glycol derivative sluggishly undergoes transesterification whereas higher homologs react smoothly.The unique template effects of the catalysts are discussed in terms of cooperation of two different tin atoms which are located in the proximity.
Highly Selective Monoacylation of Symmetric Diols Catalyzed by Metal Sulfates Supported on Silica Gel
Nishiguchi, Takeshi,Kawamine, Katsumi,Ohtsuka, Tomoko
, p. 312 - 316 (2007/10/02)
Several 1,α-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were monoacylated with high selectivity by reaction with esters in the presence of metal sulfates or hydrogen sulfates, like Ce(SO4)2 and NaHSO4, supported on silica gel.Symmetrical secondary diols were also selectively monoformylated, by reaction with ethyl formate.This method of selective esterification is simple and practical.The yield of monoester depends upon both the composition and the volume of the solvent (an ester/alkane mixture).Unsupported NaHSO4 also catalyzed monoacylation, but the selectivity was less than in monoacylations catalyzed by the supported reagent.The selectivity can be explained by the following reasons: (1) monoacylated products are formed selectively because the diol, but not the monoester, is preferentially adsorbed on the surface of the catalysts, where esterification then occurs, and (2) thin diol layers are formed on the surface of the catalysts due to limited solubility of the diols in the solvent.
