- Synthesis of aminal-type Lilium candidum alkaloids and lilaline; determination of their relative configuration by the concerted use of NMR spectroscopy and DFT conformational analysis
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We hereby report the synthesis of six racemic alkaloids isolated from Lilium candidum L. Their common structural feature is a five-membered lactam ring which is, in the case of the flavonoid alkaloid lilaline, attached to the molecule's aromatic core, while in the case of the other five compounds, it is connected to the nitrogen atom of a pyrrolinone ring by an aminal function. The syntheses of these natural products were achieved via Mannich-type alkylations through cyclic N-acyliminium ions as intermediates. Besides the synthesis, the so far unexplored stereochemistry of these natural products was determined by a combination of NMR-based proton–proton distance measurements and theoretical conformational analyses carried out at the DFT level.
- Nagy, Sándor,Szigetvári, áron,Ilkei, Viktor,Krámos, Balázs,Béni, Zoltán,Szántay, Csaba,Hazai, László
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- Recombinant Cyanobacteria for the Asymmetric Reduction of C=C Bonds Fueled by the Biocatalytic Oxidation of Water
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A recombinant enoate reductase was expressed in cyanobacteria and used for the light-catalyzed, enantioselective reduction of C=C bonds. The coupling of oxidoreductases to natural photosynthesis allows asymmetric syntheses fueled by the oxidation of water. Bypassing the addition of sacrificial cosubstrates as electron donors significantly improves the atom efficiency and avoids the formation of undesired side products. Crucial factors for product formation are the availability of NADPH and the amount of active enzyme in the cells. The efficiency of the reaction is comparable to typical whole-cell biotransformations in E. coli. Under optimized conditions, a solution of 100 mg prochiral 2-methylmaleimide was reduced to optically pure 2-methylsuccinimide (99 % ee, 80 % yield of isolated product). High product yields and excellent optical purities demonstrate the synthetic usefulness of light-catalyzed whole-cell biotransformations using recombinant cyanobacteria.
- K?ninger, Katharina,Gómez Baraibar, álvaro,Mügge, Carolin,Paul, Caroline E.,Hollmann, Frank,Nowaczyk, Marc M.,Kourist, Robert
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supporting information
p. 5582 - 5585
(2016/05/09)
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- The first experimental demonstration of side chain extension of geoporphyrins in sediments
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To investigate the formation process of high carbon number (>C 32) sedimentary porphyrins, heating experiments of several porphyrins were performed. Chromic acid oxidation of the heating products of protoporphyrin IX dimethyl ester afforded 2-methyl-3-npropylmaleimide as the predominant product among the side-chain extension products formed. On the other hand, saturated substituents of etioporphyrin were also extended on heating to slowly form normal and branched homologs. These results may suggest that the transalkylation of porphyrin side chains proceeds mainly by a regioselective mechanism involving alkyl radical addition to a vinyl group of chlorophylls or their diagenetic products.
- Asahina, Kenta,Asano, Junya,Kumagai, Gen,Satou, Mitsuru,Nomoto, Kouichi,Kashiyama, Yuichiro,Mita, Hajime,Nomoto, Shinya
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body text
p. 1267 - 1269
(2011/02/16)
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- Pyrrolidine(thi)ones Substituted by Heterocyclic Substituents in The 3-Position
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Pyrrolidine(thi)one compounds substituted by heterocyclic substituents in the 3-position, their preparation and use in pharmaceutical compositions, in particular as immunomodulators for treatment and/or inhibition of inflammatory and autoimmune diseases and haematological-oncological diseases.
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Page/Page column 22
(2009/01/20)
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- Asymmetric bioreduction of C=C bonds using enoate reductases OPR1, OPR3 and YqjM: Enzyme-based stereocontrol
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Three cloned enoate reductases from the "old yellow enzyme" family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing α,β-unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity-only the conjugated C=C bond was reduced, while isolated olefins and carbonyl groups remained intact-with excellent stereoselectivities (ees up to >99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this "enzyme-based stereocontrol" is caused by subtle differences within the active site geometries.
- Hall, Melanie,Stueckler, Clemens,Ehammer, Heidemarie,Pointner, Eva,Oberdorfer, Gustav,Gruber, Karl,Hauer, Bernard,Stuermer, Rainer,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
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experimental part
p. 411 - 418
(2009/04/10)
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- Asymmetric bioreduction of activated C=C bonds using Zymomonas mobilis NCR enoate reductase and old yellow enzymes OYE 1-3 from yeasts
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The asymmetric bioreduction of C=C-bonds bearing an electron-withdrawing group, such as an aldehyde, ketone, imide, nitro, carboxylic acid, or ester moiety by a novel enoate reductase from Zymomonas mobilis and Old Yellow Enzymes OYE 1-3 from yeasts furnished the corresponding saturated products in up to >99%ee. Depending on the substrate type, stereocontrol was achieved by variation of the substrate structure, by switching the (E/Z) geometry of the alkene or by choice of the appropriate enzyme. This substrate- or enzyme-based stereocontrol allowed access to the opposite enantiomeric products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Hall, Melanie,Stueckler, Clemens,Hauer, Bernhard,Stuermer, Rainer,Friedrich, Thomas,Breuer, Michael,Kroutil, Wolfgang,Faber, Kurt
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supporting information; experimental part
p. 1511 - 1516
(2009/04/11)
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- Method for the preparation of dicarboxylic imides
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The present invention relates to a method for the preparation of a carboxylic imide having the general formula [in-line-formulae]R1—(CO)—(NR3)—(CO)—R2 , ??(I)[/in-line-formulae] wherein a carboxylic anhydride having the general formula [in-line-formulae]R1—(CO)—O—(CO)—R2 ??(II)[/in-line-formulae] is reacted with urea or a urea derivative of the form (R3HN)—(CO)—(NR3H) in a solvent. In particular, the method can be used for the preparation of thalidomide.
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Page/Page column 3
(2008/06/13)
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- Convenient synthesis of pulchellalactam, a CD45 protein tyrosine phosphatase inhibitor from the marine fungus Corollospora pulchella, and its related compounds
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Convenient synthesis of pulchellalactam (1a) and its related compounds was accomplished. Total yields of (Z)-pulchellalactam and (E)-pulchellalactam were 55% for 5 steps and 43% for 8 steps from commercially available and inexpensive citraconic anhydride, respectively.
- Bessho, Jun-Ichiro,Shimotsu, Yasuhiko,Mizumoto, Sachiko,Mase, Nobuyuki,Yoda, Hidemi,Takabe, Kunihiko
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p. 1013 - 1016
(2007/10/03)
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- A new maturity indicator of sedimentary organic matter based on thermal fission of allylic bond in porphyrins
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A 3-ethyl-4-methylpyrrole unit in etioporphyrin was shown to be converted to a 3,4-dimethylpyrrole unit by the action of heat, which was proved to be catalyzed by Na-montmorillonite. Time courses of the reaction could be followed by analyzing 2-ethyl-3-me
- Nomoto, Shinya,Kozono, Masaki,Mita, Hajime,Shimoyama, Akira
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p. 1174 - 1175
(2007/10/03)
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- First synthesis of (R)-(-)-5-hydroxy-3-methyl-3-pyrrolin-2-one (jatropham) by lipase-catalyzed kinetic resolution
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Jatropham, (R)-(-)-5-hydroxy-3-methyl-3-pyrrolin-2-one, is synthesized in three steps from citraconic anhydride. Highly regioselective reduction of citraconimide gives racemic jatropham in high yield. Kinetic resolution of racemic jatropham using lipase is also described. (C) 1999 Elsevier Science Ltd.
- Mase, Nobuyuki,Nishi, Toshiki,Takamori, Yasuaki,Yoda, Hidemi,Takabe, Kunihiko
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p. 4469 - 4471
(2007/10/03)
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- Simple Synthesis of (+/-)-(E)-3-(4-Hydroxyphenyl)-N--2-propenamide, a Novel Phenolic Amide Derivative from the Bulbs of Lilium regale WILSON
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A synthesis of (+/-)-(E)-3-(4-hydroxyphenyl)-N--2-propenamide (7) is described.This phenolic amide was prepared in six steps with an overall yield of 46percent.
- Kuehne, Paul,Hesse, Manfred
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p. 4575 - 4580
(2007/10/02)
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- The Synthesis of 5-Ylidenepyrrol-2(5H)-ones from Maleimides and from Pyrrol-2-(5H)-ones
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A series of maleimides 5 have been prepared by reaction of the appropriate maleic anhydrides with either ammonium acetate or methylammonium acetate in boiling acetic acid.The maleimides underwent Wittig-type reactions with stabilised phosphoranes, under m
- Gill, G. Bryon,James, Gwyn D.,Oates, Karen V.,Pattenden, Gerald
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p. 2567 - 2580
(2007/10/02)
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- Reaction of Maleimides and Ethyl 3-Aminocrotonates. A Reinvestigation Leading to an Improved Synthesis of Pyrrolopyridines
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Conditions employed for the reaction between maleimides and ethyl aminocrotonates were shown to yield pyrrolopyridines rather than the previously reported pyrrolopyrroles.
- Shah, Kanhaiya R.,Blanton, C. DeWitt
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p. 502 - 508
(2007/10/02)
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- Structurel Analysis of Tetrapyrroles by Hydrogen Chemical Ionization Mass Spectrometry
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The H2 chemical ionization mass spectra of several standard porphyrins have been determined.Fragmentation proceeds via hydrogenation yielding porphyrinogens, followed by cleavage at the meso (bridge) positions to produce mono-, di-, and tripyrrolic ions.Secondary fragmentation by cleavage of substituent groups attached to the pyrrole rings may then occur.Identification of these fragments and the corresponding molecular ions produces considerable structural information on the parent molecule.In certain cases these data are sufficient to distinguish porphyrin type (positional) isomers.In addition information of substituents at meso positions may be retained.
- Shaw, George J.,Eglinton, Geoffrey,Quirke, J. Martin E.
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p. 2014 - 2020
(2007/10/02)
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- PETROPORPHYRINS - II. THE PRESENCE OF PORPHYRINS WITH EXTENDED ALKYL SUBSTITUENTS
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The vanadyl porphyrins from Boscan oil (Cretaceous, W.Venezuela) were isolated as 3 fractions, and degraded to maleimides (1H-pyrrole-2,5-diones) by chromic acid.Analysis of the products by GC-MS, using multiple ion detection to enhance sensitivity, revealed a major homologous series of 3-Me components with n-alkyl side chains extending to C11, and a minor series with branched alkyl side chains, the Me branch being at C-1.The origin of the extended alkyl groups is discussed.
- Martin, J.,Quirke, E.,Shaw, George J.,Soper, Paul D.,Maxwell, James R.
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p. 3261 - 3268
(2007/10/02)
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