- Chiral hypervalent iodine(III) catalyst promotes highly enantioselective sulfonyl-and phosphoryl-oxylactonizations
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An efficient enantioselective hypervalent iodine promoted oxylactonization of 4-pentenoic acids has been achieved using stoichiometric or a catalytic amount of chiral aryl-λ3-iodane. This reaction provides straightforward access to a wide range of sulfonyloxy-and phosphoryloxy-γ-butyrolactones in respectable yields with moderate to excellent enantioselectivities.
- Gelis, Coralie,Dumoulin, Audrey,Bekkaye, Mathieu,Neuville, Luc,Masson, Géraldine
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supporting information
p. 278 - 281
(2017/11/27)
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- A total synthesis of natural Rhizobialide
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Natural butanolide Rhizobialide was synthesized for the first time in enantiopure form with the stereogenic center derived from glutamic acid.
- Guan, Jing,Zou, Yang,Gao, Po,Wu, Yikang,Yue, Zhengyu
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experimental part
p. 1613 - 1617
(2011/07/08)
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- Synthesis of C1-C11 fragment of annonacin: A polyketide acetogenin of Annonaceae
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(4R, 10S)-Methyl tri-isopropylsilyloxy-4-tert-butyldimethylsilyloxy-10-tert-amyloxy-11- undecanoate 1 has been synthesized from L-glutamic acid. This compound is a key intermediate in the total synthesis of annonacin, an acetogenin of Annonaceae.
- Figadere,Franck,Cave
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p. 1637 - 1640
(2007/10/02)
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- Substrate structure and incubation-parameter-dependent selectivities in chiral discrimination of galactopyranosides by β-galactosidase hydrolysis
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Mono-β-galactopyranosides of (+/-)-propane-1,2-diol, (+/-)-butane-1,3-diol, (+/-)-pentane-1,4-diol, (+/-)-butan-2-ol, (+/-)-pentan-2-ol and (+/-)-1,2-O-isopropylideneglycerol were synthesized by the Koenigs-Knorr reaction using hydroxycarbonyl compounds as precursors for the diolic substrates.Hydrolysis of 3-hydroxybutyl β-D-galactopyranoside 18 by β-galactosidases from Eschrichia coli, Aspergillus oryzae, Kluyveromyces lactis and Bacillus circulans, respectively, resulted in each case in an enantiomeric enrichment of the released diol.This was most significant with the E. coli enzyme and and increased with higher reaction temperature and shorter incubation periods.Under standartized conditions, cleavage of all synthesized galactopyranosides by this enzyme showed the highest stereoselectivity for butane-1,3-diol, butan-2-ol and isopropylideneglycerol with enantiomeric excesses in the range 60-75percent.For compounds with structural similarity to the natural substrate lactose, enhanced stereodiscriminations were expected.However, this could not be confirmed and instead a specific hydrophobic interaction is suggested to play a crucial role.
- Werschkun, Barbara,Koenig, Wilfried A.,Kren, Vladimir,Thiem, Joachim
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p. 2459 - 2466
(2007/10/02)
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- Enantioenriched N-(2-Chloroalkyl)-3-acetoxypiperidines as Potential Cholinotoxic Agents. Synthesis and Preliminary Evidence for Spirocyclic Aziridinium Formation.
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The syntheses of six enantioenriched analogs representing cyclic forms of acetylcholine are reported. (S)- and (R)-N-(2-chloroethyl)-3-acetoxypiperidine and (R,R)-, (R,S)-, (S,R)-, and (S,S)-N-(2-chloropropyl)-3-acetoxypiperidine have been synthesized from (R)- or (S)-3-hydroxypiperidine in five steps. (R)- and (S)-3-hydroxypiperidine were accessed via parallel stereospecific routes from d- and l-glutamic acid, and through fractional recrystallization of diastereomeric tartranilic acid salts. (S)-N-(2-Chloroethyl)-3-acetoxypiperidine was reacted with silver perchlorate to form a spirocyclic aziridinium analog of acetylcholine as evidenced by a characteristic 1H NMR shift for the aziridinium methylene groups.
- Huh, Nam,Thompson, Charles M.
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p. 5935 - 5950
(2007/10/02)
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- Enantiospecific Preparation of the Lactone Fragment of Murisolin
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Both enantiomers (R) and (S) of the functionalized unsaturated γ-lactone moiety of the acetogenin murisolin have been enantiospecifically synthezised from L and D-glutamic acid respectively.
- Harmange, Jean-Christophe,Figadere, Bruno,Hocquemiller, Reynald
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p. 347 - 350
(2007/10/02)
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