Xi:Irritant;
2216-51-5Relevant articles and documents
Acceleration of acid-catalyzed hydrolysis in a biphasic system by sodium tetracyanocyclopentadienides
Sakai, Takeo,Bito, Mariko,Itakura, Makoto,Sato, Honami,Mori, Yuji
, p. 930 - 934 (2016)
The hydrolysis of tert-butyldimethylsilyl L-menthyl ether (3) in a CH2Cl2-1 M HCl biphasic solvent system was accelerated by the addition of sodium tetracyanocyclopentadienides 1. Particularly, the reaction rate was enhanced using sodium salt 1a-c with a lipophilic substituent on the cyclopentadienide ring. From the results obtained by a triphasic experiment, hydrolysis proceeds via the formation of hydronium ion 2 in the aqueous phase by ion exchange, followed by the transfer of 2 to the CH2Cl2 phase.
Selective cleavage of allyl ethers
Lee, Jinhwa,Cha, Jin Kun
, p. 3663 - 3666 (1996)
A simple, one-step method for the selective cleavage of allyl ethers to alcohols has been developed by use of Ti(O-i-Pr)4 and a commercially available Grignard reagent.
Synthesis of new mixed (-)-menthylalkyltin dihydrides. stereoselective reduction of chiral and prochiral ketones
Terraza, V. Fabricio,Gerbino, Darío C.,Podestá, Julio C.
, (2021)
This paper reports de synthesis of a series of (-)-menthylalkyltin dihydrides, (-)-MenRSnH2 (R = Me, n-Bu, i-Pr, t-Bu, Neophyl), starting from (-)-menthyltrimethyltin. The new (-)-menthylalkyltin dihydrides 12–16 were used in a study on the stereoselective reduction of chiral (-)-menthone under different reaction conditions. Also the results obtained in the reductions of prochiral acetophenone (27) and 2-acetylnaphthalene (28), with (-)-menthylmethyl- (12) and (-)-menthyli-propyltin (14) dihydrides are informed. Some physical properties as well as full 1H-, 13C-, and 119Sn NMR data of the new organotin compounds are informed.
Chromatography-free Pd-catalyzed deprotection of allyl ethers using PS-DEAM as a scavenger of boronic acids and Pd catalyst
Tsukamoto, Hirokazu,Suzuki, Takamichi,Sato, Masanori,Kondo, Yoshinori
, p. 8438 - 8441 (2007)
Polystyrene-bound diethanolamine (PS-DEAM) work-up for a newly developed Pd(PPh3)4-catalyzed cleavage of allylic alkyl ethers using phenylboronic acid can effectively release Pd-free parent alcohols. Furthermore, chromatography-free deallylation can be conducted by using vinylboronic anhydride pyridine complex as an allyl scavenger with a catalytic amount of Pd(OAc)2 and 4-(diphenylphosphino)benzoic acid instead of Pd(PPh3)4 to yield the desired products in high purities and yields after removal of volatile byproducts and the phosphine-derived contaminants by evaporation and sequestration through acid-base interaction with PS-DEAM, respectively.
A thermostable variant of Bacillus subtilis esterase: Characterization and application for resolving dl-menthyl acetate
Gong, Yi,Xu, Guo-Chao,Zheng, Gao-Wei,Li, Chun-Xiu,Xu, Jian-He
, p. 1 - 8 (2014)
Bacillus subtilis esterase (BSE) exhibits high activity, extraordinary substrate/product tolerance and excellent enantioselectivity in the production of l-menthol through enantioselective hydrolysis of dl-menthyl acetate. However, rapid inactivation of wild-type BSE at elevated temperatures often hampers its applications. In this work, directed evolution was used to create thermostable mutants of BSE. After screening and recombination of beneficial mutations, BSEV4 was chose for the best mutant. The BSEV4 had half-lives of 462, 248 and 0.34 h at 30, 40 and 50 °C, respectively, which were 5.6, 4.1 and 2.0 folds longer than those of BSEWT. Moreover, BSEV4 showed an increase of 4.5 °C in T5015 and a higher temperature optimum compared with the wild-type enzyme. In the kinetic resolution of dl-menthyl acetate at 1.0 M substrate loading, BSEV4 displayed improvements in operational stability than BSEWT, leading to a 1.5-fold higher total turnover number at 45 °C. The model structure of BSEV4 with four mutations, built with a highly homologous p-nitrobenzyl esterase (PDB ID: 1QE3) as the template, revealed that the newly formed hydrogen bonds and ionic bonds were beneficial for enhancing the thermostability of BSE.
A novel benzoyl-type fluorous protecting group for use in fluorous synthesis
Miura, Tsuyoshi,Satoh, Ai,Goto, Kohtaro,Murakami, Yasuoki,Imai, Nobuyuki,Inazu, Toshiyuki
, p. 3 - 6 (2005)
TfBz-OH, a novel benzoyl-type fluorous protecting reagent, has been easily prepared. It was found that the TfBz (trisfluorous chain-type benzoyl) group can be successfully introduced onto a hydroxyl function, removed in high yield, and recycled after deprotection. The use of the TfBz group makes it possible to synthesize an oligosaccharide by minimal column chromatography purification, because each synthetic intermediate is easily purified simply by fluorous-organic solvent extraction.
Chiral pyridinium-based ionic liquids containing the (1R,2S,5R)-(-)-menthyl group
Pernak, Juliusz,Feder-Kubis, Joanna
, p. 1728 - 1737 (2006)
A novel class of chiral pyridinium salts in which the chirality resides in the cation have been prepared and characterized. The physicochemical and anti-microbial properties have been determined. The group of prepared salts contained chiral ionic liquids and decomposable chiral pyridinium chlorides.
Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst
Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana
, (2022/04/03)
One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.
Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
Kathe, Prasad M.,Berkefeld, Andreas,Fleischer, Ivana
supporting information, p. 1629 - 1632 (2021/02/09)
This report discloses the deallylation of O - and N -allyl functional groups by using a combination of a Ni-H precatalyst and excess Bronsted acid. Key steps are the isomerization of the O - or N -allyl group through Ni-catalyzed double-bond migration followed by Bronsted acid induced O/N-C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
