108-84-9Relevant academic research and scientific papers
Enzymatic kinetic resolution of aliphatic sec-alcohols by LipG9, a metagenomic lipase
Bandeira, Pamela T.,Alnoch, Robson C.,De Oliveira, Alfredo R.M.,De Souza, Emanuel M.,De O.P., Fábio,Krieger, Nadia,Piovan, Leandro
, p. 58 - 63 (2016/01/30)
Bioprospection for new enantioselective enzymes for application in organic synthesis is a prominent area of investigation in biocatalysis. In this context, here we present the evaluation of an immobilized lipase isolated from a metagenomic library (LipG9) for the enzymatic kinetic resolution (EKR) of aliphatic sec-alcohols, which are still challenging substrates, since low enantioselectivity values are usually observed for these resolutions. LipG9 was successfully employed in EKR of aliphatic alcohols, which were resolved with satisfactory conversions (19-59%) and enantiomeric excesses for alcohols (26-88%) and esters (30-96%) by transesterification reactions, demonstrating that its performance is equal to or better than commercially available enzymes for the same reaction.
Syntheses of enantiopure aliphatic secondary alcohols and acetates by bioresolution with lipase B from candida antarctica
Ferreira, Hercules V.,Rocha, Lenilson C.,Severino, Richele P.,Porto, Andre L. M.
, p. 8955 - 8967,13 (2020/08/31)
The lipase B from Candida antarctica (Novozym 435, CALB) efficiently catalyzed the kinetic resolution of some aliphatic secondary alcohols: (±)-4-methylpentan- 2-ol (1), (±)-5-methylhexan-2-ol (3), (±)-octan-2-ol (4), (±)-heptan-3-ol (5) and (±)-oct-1- en-3-ol (6). The lipase showed excellent enantioselectivities in the transesterifications of racemic aliphatic secondary alcohols producing the enantiopure alcohols (>99% ee) and acetates (>99% ee) with good yields. Kinetic resolution of rac-alcohols was successfully achieved with CALB lipase using simple conditions, vinyl acetate as acylating agent, and hexane as non-polar solvent.
Alkylchlorotins grafted to cross-linked polystyrene beads by a -(CH 2)n spacer (n-4, 6, 11): Selective, clean and recyclable catalysts for transesterification reactions
Camacho-Camacho, Carlos,Biesemans, Monique,Van Poeck, Manu,Mercier, Frederic A. G.,Willem, Rudolph,Darriet-Jambert, Karine,Jousseaume, Bernard,Toupance, Thierry,Schneider, Uwe,Gerigk, Ursula
, p. 2455 - 2461 (2007/10/03)
Insoluble polystyrene grafted compounds of the type (P-H) (1-t)(P-(CH2)nSnBupCl 3-p,}t, (P-H)(1-t){P-(CH2) nSnBuO)t and (P-H)(1-t)[(P-(CH 2)nSnBuCl}2O]t/2, in which (P-H) is a cross-linked polystyrene; n=4, 6, and 11; p=0 and 1; and t the degree of functionalisation, were synthesised from Amberlite XE-305, a polystyrene cross-linked with divinylbenzene. The compounds were characterised by using elemental analysis, and IR, Raman, solid-state 117Sn NMR, and 1H and 119Sn high-resolution MAS NMR spectroscopy. The influence of the spacer length and the tin functionality on the catalytic activity of these compounds, as well as their recycling ability, was assessed in the transesterifica tion reaction of ethyl acetate with various alcohols. These studies showed significant differences in the activity of the catalysts interpreted in terms of changes in the mobility of the catalytic centres. Some of the supported catalysts could be recycled at least seven times without noticeable loss of activity. The residual tin content in the reaction products was found to be as low as 3 ppm.
Electrophilic Cleavage of Cyclopropanes. Acetolysis of Alkylcyclopropanes
Wiberg, Kenneth B.,Kass, Steven R.
, p. 988 - 995 (2007/10/02)
The solvent kinetic hydrogen isotope effect showed that proton transfer is at least partially rate determining for the acetolysis of cyclopropanes which span a range of 1010 in reactivity.The energies and structures of protonated cyclobutanes were calculated and provide an explanation for the large difference in reactivity between cyclopropanes and cyclobutanes despite their similarity in enthalpies of reaction.The rates and products of acetolysis of a series of alkyl-substituted cyclopropanes were examined.The data, along with the results of ab initio calculations, indicate that for alkyl-substituted cyclopropanes, the protonated species is highly unsymmetrical.Cleavage of the cyclopropane ring always occurs so that the nucleophile becomes attached to the most substituted carbon, but the proton may attack either of the remaining carbons.Proton attack may lead to either retention or inversion of configuration depending on the orientation of the attacking proton with respect to the ring.
Acid-induced 13C Nuclear Magnetic Resonance Chemical Shift Changes of Ether and Ester Carbon Atoms
Begtrup, Mikael
, p. 1609 - 1618 (2007/10/02)
13C N.m.r. chemical shifts of ehters dissolved in tetrachloromethane are displaced on addition of trifluoroacetic acid.The displacements result from independent interactions of the acid with the substrate oxygen atoms and alkyl residues.The structure-dependent and stereoselective shift changes are useful for signal assignments, structure determination, conformational analysis, assessment of the distribution of rapidly interconverting conformers of esters, and estimation of the relative basicity of ethers.
1-Substituted Imidazoles as Useful Catalysts for Acylation of Alcohols
Kamijo, Tetsuhide,Yamamoto, Ryoji,Harada, Hiromu,Iizuka, Kinji
, p. 3724 - 3727 (2007/10/02)
Acylation of alcohols with acid anhydrides or acid halides could be considerably accelerated by adding 1-substituted imidazoles as catalysts.The acylation with acid halides required the addition of triethylamine to capture the resulting acid. 1-Isopropyl-5-methylimidazole and 1-(4-methoxybenzyl)-5-methylimidazole showed higher catalytic activities than 4-dimethylaminopyridine (DMAP) for acylation of primary and secondary alcohols. Keywords ---- 1-substituted imidazole; acylating catalyst; 1-isopropylimidazole; 1-isopropyl-5-methylimidazole; 1-(4-methoxybenzyl)-5-methylimidazole; 4-dimethylaminopyridine
1-ACYL-3-SUBSTITUTED IMIDAZOLIUM SALTS AS HIGHLY REACTIVE ACYLATING AGENTS
Kamijo, Tetsuhide,Yamamoto, Ryoji,Harada, Hiromu,Iizuka, Kinji
, p. 4242 - 4244 (2007/10/02)
1-Acylimidazoles could be highly activated for acylation by the quarternizing with benzyl halides. 1-Acyl-3-benzylimidazolium halides were powerful acylating agents.Alcohols, phenols, and amines were converted to the corresponding esters and amides in excellent yields under mild conditions.Keywords - 1-acyl-3-substituted imidazolium salts; acylating agents; 1-acylimidazoles; 1-acetyl-3-benzylimidazolium bromide; 1-benzoyl-3-benzylimidazolium bromide
Synthetic applications of α-hydroxydiazenes. III. Uncatalyzed and phenol catalyzed hydroalkylation of alkenes and of azobenzene with alkylazodiphenylmethanols
Yeung, Dominic W. K.,Warkentin, John
, p. 2386 - 2394 (2007/10/02)
Alkylazodiphenylmethanols (C6H5)2C(OH)N=NR, (R = CH(CH3)2, CH2CH3, CH3), when decomposed in the presence of olefinic substrates or in the presence of azobenzene, hydroalkylate those substrates.Addition of R and H across the double bond of an unsymmetric alkene occurs with the regiochemistry expected for a radical mechanism, in which the grooup R adds first.Radical intermediates from decomposition of alkylazodiphenylmethanols have been demonstrated earlier with spin trapping experiments.The fact that addition of phenol can enhance the yield of hydroalkylation product suggests that the process is a radical chain reaction, with chain carrying steps consisting of the reactions: (i) R. + CH2=CHY -> RCH2C.HY (ii) RCH2C.HY + (C6H5)2C(OH)N2R -> RCH2CH2Y + (C6H5)2CO + N2 + R..One deuterioalkylation and some yield-optimizing experiments are also reported.
