71804-27-8Relevant academic research and scientific papers
Diastereoselective photocycloaddition reactions of 2-naphthalenecarboxylates and 2,3-naphthalenedicarboxylates with furans governed by chiral auxiliaries and hydrogen bonding interactions
Maeda, Hajime,Koshio, Norihiro,Tachibana, Yuko,Chiyonobu, Kazuhiko,Konishi, Gen-ichi,Mizuno, Kazuhiko
, p. 7 - 17 (2017/09/12)
By using chiral auxiliaries and hydrogen bonding interactions, we have developed diastereoselective photocycloaddition of 2-naphthalenecarboxylates and 2,3-naphthalenedicarboxylates with furan derivatives. In photoreactions of (?)-menthyl 2-naphthalenecarboxylate with furan and 3-furanmethanol, respective maximum 48% and 40% diastereomeric excesses (d.e.) are observed. In photoreactions of di-8-phenyl-(?)-menthyl 2,3-naphthalenedicarboxylate with 3-furanmethanol, maximum 67% d.e. is obtained. Use of solvents of low polarity, low temperatures and low furan concentration leads to increased diastereoselectivities. Variable-temperature (VT) NMR and fluorescence quenching studies indicate that hydrogen bonding interactions between the carbonyl oxygen of naphthalenecarboxylic acid esters and the OH group in 3-furanmethanol take place in both the ground and excited states. The results of computational studies show that geometries of C2 symmetric naphthalenedicarboxylate reactants are important in governing the high diastereoselectivity in the photoreactions of 2,3-naphthalenedicarboxylates.
Asymmetric 1,2-Perfluoroalkyl Migration: Easy Access to Enantioenriched α-Hydroxy-α-perfluoroalkyl Esters
Wang, Pan,Feng, Liang-Wen,Wang, Lijia,Li, Jun-Fang,Liao, Saihu,Tang, Yong
, p. 4626 - 4629 (2015/04/27)
This study has led to the development of a novel, highly efficient, 1,2-perfluoro-alkyl/-aryl migration process in reactions of hydrate of 1-perfluoro-alkyl/-aryl-1,2-diketones with alcohols, which are promoted by a Zn(II)/bisoxazoline and form α-perfluoro-alkyl/-aryl-substituted α-hydroxy esters. With (-)-8-phenylmenthol as the alcohol, the corresponding menthol esters are generated in high yields with excellent levels of diastereoselectivity. The mechanistic studies show that the benzilic ester-type rearrangement reaction takes place via an unusual 1,2-migration of electron-deficient trifluoromethyl group rather than the phenyl group. The overall process serves as a novel, efficient, and simple approach for the synthesis of highly enantioenriched, biologically relevant α-hydroxy-α-perfluoroalkyl carboxylic acid derivatives.
Total synthesis of (-)-chokol A by an asymmetric domino Michael addition-Dieckmann cyclization
Groth, Ulrich,Kesenheimer, Christian,Kreye, Paul
, p. 2223 - 2226 (2007/10/03)
A convergent and asymmetric total synthesis of (-)-chokol A was accomplished in six steps starting from the α,β-unsaturated ester (E)-9 in an overall yield of 27% with an enantiomeric excess of 95%. The key step of this synthesis is the asymmetric tandem conjugate addition-Dieckmann cyclization of the higher-order cuprate 8 derived from vinyl bromide 7 with the α,β-unsaturated ester (E)-9. Georg Thieme Verlag Stuttgart.
Asymmetric induction in Darzens condensation by means of (-)-8-phenylmenthyl and (-)-menthyl auxiliaries
Takagi, Ryukichi,Kimura, Jyunji,Shinohara, Yoshihiro,Ohba, Yuko,Takezono, Kyoko,Hiraga, Yoshikazu,Kojima, Satoshi,Ohkata, Katsuo
, p. 689 - 698 (2007/10/03)
Asymmetric Darzens condensation of benzaldehyde and various ketones has been investigated. The condensation of acetophenone, propiophenone and symmetric ketones with (-)-8-phenylmenthyl halogenoacetates 3a,b afforded the corresponding glycidic esters cis-12, cis-13 and 15-19 in 77-96% de, respectively, as the major products. Aza-Darzens condensation between N-benzylideneaniline and 3a occurred to give the trans-aziridine 21 as the major isomer in >85% de. The stereochemistry of the major diastereoisomers of cis-12 and 18 was confirmed by their conversion into the known optically active diols 22 and 24. The configuration of the major product of cis-12 was determined to be 2R,3R and that of 18 to be 2R. The geometric and disastereofacial selectivities were understandable in terms of the open-chain or non-chelated antiperiplanar transition state model in the initial aldol-type reaction.
Asymmetric Synthesis of L-Alanine and L-Phenylalanine by a Phase-Transfer Alkylation Reaction
Fasth, Karl-Johan,Antoni, Gunnar,Laengstroem, Bengt
, p. 3081 - 3084 (2007/10/02)
The asymmetric syntheses of enantiomerically enriched L-alanine and L-phenylalanine t1/2 20.4 min for 11C) by phase-transfer alkylation of (-)-8-phenylmenthan-3-yl N-(diphenylmethylene)-glycenate with methyl and benzyl iodides, respectively, are presented.The total synthesis times were 35-55 min, from the start of synthesis of the methyl and (α-11C>benzyl iodides.The products were obtained in 15-40percent (decay corrected) radiochemical yields and higher than 98percent radiochemical purities.The enantiomeric purities of the amino acids were determined to be 52-55percent enantiomeric excess (e.e).In a typical run 600 MBq of L-alanine was obtained, starting with 5.2 GBq of carbon dioxide.
Preparation of Pure (-)-(1R,2S,5R)-2-(1-Methyl-1-phenylethyl)-5-methylcyclohexanol in Larger Amounts
Herzog, Heinz,Scharf, Hans-Dieter
, p. 420 - 421 (2007/10/02)
A method is described for the separation of (-)-(1R,2S,5R)-2-(1-methyl-1-phenylethyl)-5-methylcyclohexanol (1; 8-phenylmenthol) in preparative amounts in the form of its chloroacetate 3 from the accompanying diastereomer 2, which is formed according to Corey's synthesis.
