95513-34-1Relevant academic research and scientific papers
Development of novel chiral dopants to be used in ferroelectric liquid crystal system
Kayani, Zohra N.,Lewis, Robert A.,Naseem, Shahzad
, p. 74 - 88 (2013/05/08)
The study of chiral dopant and its application in liquid crystal system is one of the largest area of research in fluids leading to technological application in the field of display devices. Chiral dopant when mixed with achiral host mixture forms ferroelectric liquid crystal to be used in surface stabilised liquid crystal devices. 4-(pentyl, heptyl, nonyl)-2, 3 difluoro terphenyl nitriles and (S)-(-)-1-cyno-2-methylbutyl-4-pentyl-difluoroterphenyl- 4′-carboxylate were synthesised and mixed with achiral host mixture HM1 with the percentage of 3 and 7. Ferroelectric properties of synthesised FLC 1 were studied.
A convenient method for the kinetic resolution of racemic 2-hydroxyalkanoates using diphenylacetic anhydride (DPHAA) and a chiral acyl-transfer catalyst
Nakata, Kenya,Sekiguchi, Akihiro,Shiina, Isamu
experimental part, p. 1610 - 1619 (2012/01/03)
Diphenylacetic anhydride (DPHAA) was found to be a useful reagent for the kinetic resolution of racemic 2-hydroxyalkanoates in the presence of a catalytic amount of (R)-benzotetramisole ((R)-BTM). The combined use of DPHAA and (R)-BTM effectively produced a variety of the optically active 2-hydroxyalkanoates and the corresponding 2-acyloxyalkanoates from racemic 2-hydroxyalkanoates (s-values = 42-177). A fairly broad substrate scope was demonstrated by this novel chiral induction system. We also revealed that the use of only 0.3 equiv of DPHAA is enough to provide the optically active 2-acyloxyalkanoates in good yields and with excellent ee's by the added use of 0.3 equiv of pivalic anhydride for the kinetic resolution of the racemic 2-hydroxyalkanoates. Copyright
METHOD FOR PRODUCING OPTICALLY ACTIVE 2-HYDROXY ESTER AND NOVEL INTERMEDIATE COMPOUND
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Page/Page column 6-10, (2012/01/13)
Disclosed is a method for producing an optically active 2-hydroxy ester, comprising selectively esterifying one enantiomer of a racemic 2-hydroxy ester in a solvent containing a catalyst such as tetramisole or benzotetramisole, and a carboxylic acid anhydride, or a carboxylic acid anhydride and a carboxylic acid. In particular, in the case where the solvent contains a carboxylic acid anhydride, but does not contain a carboxylic acid, as the carboxylic acid anhydride, a carboxylic acid anhydride containing a tertiary or quaternary carbon atom in the a-position is used. On the other hand, in the case where the solvent contains a carboxylic acid anhydride and a carboxylic acid, as the carboxylic acid, a carboxylic acid containing a tertiary or quaternary carbon atom in the a-position is used.
Kinetic resolution of the racemic 2-hydroxyalkanoates using the enantioselective mixed-anhydride method with pivalic anhydride and a chiral acyl-transfer catalyst
Shiina, Isamu,Nakata, Kenya,Ono, Keisuke,Sugimoto, Masuhiro,Sekiguchi, Akihiro
supporting information; experimental part, p. 167 - 172 (2010/03/26)
A variety of optically active 2-hydroxyalkanoates and the corresponding 2-acyloxyalkanoates are produced by the kinetic resolution of racemic 2-hydroxyalkanoates by using achiral 2,2-diarylacetic acid with hindered carboxylic anhydrides as the coupling reagents. The combined use of diphenylacetic acid, pivalic anhydride, and (+)-(R)-benzotetramisole ((R)-BTM) effectively produces (S)-2-hydroxyalkanoates and (R)-2-acyloxyalkanoates from the racemic 2-hydroxyalkanoates (s-values = 47-202). This protocol directly provides the desired chiral 2-hydroxyalkanoate derivatives from achiral diarylacetic acid and racemic secondary alcohols that do not include the sec-phenethyl alcohol moiety by using the transacylation process to generate the mixed anhydrides from the acid components with bulky carboxylic anhydrides under the influence of the chiral acyl-transfer catalyst. The transition state that provides the desired (R)-2-acyloxyalkanoate from (R)-2-hydroxyalkanoate included in the racemic mixture is disclosed by DFT calculations, and the structural features of the transition form are also discussed.
Total synthesis of myxovirescin A1
Fuerstner, Alois,Bonnekessel, Melanie,Blank, Jarred T.,Radkowski, Karin,Seidel, Guenter,Lacombe, Fabrice,Gabor, Barbara,Mynott, Richard
, p. 8762 - 8783 (2008/04/03)
A convergent total synthesis of the antibiotic macrolide myxovirescin A1 (1) is described that is largely based on reagent- and catalyst-controlled transformations. This includes a highly regioselective Negishi reaction of dibromo-alkene 48 with an alkynyl-zinc reagent, and a palladium catalyzed alkyl-Suzuki coupling of the resulting enyne derivative 12 with the 9-BBN-adduct derived from alkene 61. The latter was obtained via an asymmetric hydrogenation of the chlorinated β-ketoester 49 and an anti-selective oxyallylation of the functionalized aldehyde 53 as the key steps. The preparation of the bis-borylated allyl-donor 57 used in the oxyallylation step, however, required careful optimization and led to important insights into the nature of the classical hydroborating agent "di(isopinocampheyl)borane (IpC2BH)". It was unambiguously shown by X-ray crystallography that in the solid state this compound is dimeric, but it is prone to undergo an essentially quantitative mono-deborylation when dissolved in CH 2Cl2 or benzene; its composition in ethereal solvents is even more complex as evident from 11B NMR data. Product 71 derived from 12 and 61 was elaborated into the enyne-yne derivative 75, which served as the substrate for an exquisitely selective ring closing alkyne metathesis reaction (RCAM) catalyzed by the molybdenum tris-amido complex 20 activated in situ with CH2Cl2. The resulting cyclic enyne 76 was subjected to a ruthenium catalyzed trans-hydrosilylation/proto-desilylation tandem. Although [Cp*Ru(MeCN)3]PF6 had previously been recommended as catalyst of choice for trans-hydrosilylation reactions of internal alkynes, this complex failed to afford the desired product, whereas its sterically less hindered congener [CpRu(MeCN)3]PF6 permitted the reaction to be performed in appreciable yield, but at the expense of a lower stereoselectivity. AgF-mediated proto-desilylation of the isomeric silanes 79 and 80 followed by cleavage of the remaining acetal protecting groups afforded myxovirescin A1 and its hitherto unknown 14Z-isomer 81, respectively.
Non-peptide Renin Inhibitors Containing 2-(((3-Phenylpropyl)phosphoryl)oxy)alkanoic Acid Moieties as P2-P3 Replacements
Raddatz, Peter,Minck, Klaus-Otto,Rippmann, Friedrich,Schmitges, Claus-Jochen
, p. 486 - 497 (2007/10/02)
A series of novel renin inhibitors containing 2-(((3-phenylpropyl)phosphoryl)oxy)alkanoic acid moieties as P2-P3 surrogates are presented.The P2-P3 mimetics were obtained from (ω-phenylalkyl)phosphinic acids 1a-c and 2-hydroxyalkanoic acid benzyl esters 2a-f by N,N'-dicyclohexylcarbodiimide-mediated coupling and subsequent oxidation with sodium metaperjodate.Ester cleavage of these derivatives and coupling with P1-P'1 transition-state mimetics I-VII provided highly selective compounds with inhibitory potencies in the lower nanomolar range.Small renin inhibitors, such as analogues 8c and 8h with molecular weights of 539 and 537, respectively, could be prepared.These compounds exhibited IC50 values of about 20 nM against human plasma renin.Compound 7i was examined in vivo for its hypotensive effect.In salt-depleted cynomolgus monkeys, 7i inhibited plasma renin activity almost completely and lowered blood pressure after oral adiministration of a dose of 30 mg/kg.
α-Amino Acids as Chiral Educts for Asymmetric Products. Chirospecific Syntheses of the 5-Butyl-2-heptylpyrrolidines from Glutamic Acid
Shiosaki, Kazumi,Rapoport, Henry
, p. 1229 - 1239 (2007/10/02)
Both enantiomers of trans-5-butyl-2-heptylpyrrolidine, an active and major component in the repellent venom of the ant Solenopsis fugax, have been synthesized with very high diastereomeric and optical purity from glutamic acid.Both enantiomers of the cis isomer also have been synthesized in an extension of our methodology to encompass the preparation of both cis and trans, optically pure, 2,5-disubstituted pyrrolidines and because of their potential entomological interest.Initially, a sulfide contraction process efficiently introduces the first side chain onto a pyroglutamate intermediate.Various strategies to elaborate the second side chain have been developed along with methods to control and establish the relative steroechemistry at C-2 and C-5 of the pyrrolidine ring with high selectivity. 2,5-Dialkyl-1-pyrrolidines, which also have been identified in the ant venom, can be prepared by these processes as well with specific absolute stereochemistry.
