- Mixed Anhydride Intermediates in the Reaction of 5(4H)-Oxazolones with Phosphate Esters and Nucleotides
-
5(4H)-Oxazolones can be formed through the activation of acylated α-amino acids or of peptide C termini. They constitute potentially activated intermediates in the abiotic chemistry of peptides that preceded the origin of life or early stages of biology and are capable of yielding mixed carboxylic-phosphoric anhydrides upon reaction with phosphate esters and nucleotides. Here, we present the results of a study aimed at investigating the chemistry that can be built through this interaction. As a matter of fact, the formation of mixed anhydrides with mononucleotides and nucleic acid models is shown to take place at positions involving a mono-substituted phosphate group at the 3’- or 5’-terminus but not at the internal phosphodiester linkages. In addition to the formation of mixed anhydrides, the subsequent intramolecular acyl or phosphoryl transfers taking place at the 3’-terminus are considered to be particularly relevant to the common prebiotic chemistry of α-amino acids and nucleotides.
- Liu, Ziwei,Rigger, Lukas,Rossi, Jean-Christophe,Sutherland, John D.,Pascal, Robert
-
-
Read Online
- Photophysical Properties of Tyrosine and Its Simple Derivatives Studied by Time-Resolved Fluorescence Spectroscopy, Global Analysis, and Theoretical Calculations
-
The photophysical properties of tyrosine and its derivatives with free and blocked functional groups in water were studied by steady-state and time-resolved fluorescence spectroscopy and global analysis. Tyrosine fluorescence intensity decays in water at
- Guzow, Katarzyna,Ganzynkowicz, Robert,Rzeska, Alicja,Mrozek, Justyna,Szabelski, Mariusz,Karolczak, Jerzy,Liwo, Adam,Wiczk, Wies?aw
-
-
Read Online
- Diastereoselectivity in prebiotically relevant 5(4H)-oxazolone-mediated peptide couplings
-
A stereochemical study of a potentially prebiotic peptide-forming reaction was carried out as the first part of a systems chemistry investigation of potential paths for symmetry breaking. Substantial diastereomeric excesses result from a fast epimerization of the 5(4H)-oxazolone intermediate in aqueous solution. The Royal Society of Chemistry.
- Beaufils, Damien,Danger, Gregoire,Boiteau, Laurent,Rossi, Jean-Christophe,Pascal, Robert
-
supporting information
p. 3100 - 3102
(2014/03/21)
-
- Asymmetric synthesis of unnatural amino acids and tamsulosin chiral intermediate
-
An efficient and enantioselective hydrogenation of N-acetylamino phenyl acrylic acids was successfully developed by using ruthenium catalyst. This methodology is important in the field of pharmaceuticals and provides a new process for the preparation of unnatural amino acids and tamsulosin chiral intermediate.
- Arava, Veera Reddy,Amasa, Srinivasulu Reddy,Goud Bhatthula, Bharat Kumar,Kompella, Laxmi Srinivas,Matta, Venkata Prasad,Subha
-
p. 2892 - 2897
(2013/09/02)
-
- Synthesis and application of peripherally alkyl-functionalized dendritic pyrphos ligands: Homogeneous-supported catalysts for enantioselective hydrogenation
-
A new series of dendritic ligands with a chiral diphosphine located at the focal point have been synthesized through coupling of (R,R)-3,4-bis(biphenylphosphino)pyrrolidine (pyrphos) with peripherally alkyl-functionalized benzoic acid dendrons. These ligands were employed in the Rh-catalyzed asymmetric hydrogenation of prochiral dehydroamino acids, exhibiting excellent catalytic activities and enantioselectivities. The second-generation dendritic catalyst could be recovered by simple liquid-liquid biphasic separation and reused four times without serious loss of its activity and selectivity.
- Yi, Bing,He, Hua-Ping,Fan, Qing-Hua
-
experimental part
p. 82 - 85
(2010/04/25)
-
- Synthesis of a novel spiro bisphosphinite ligand and its application in Rh-catalyzed asymmetric hydrogenation
-
A novel, chiral bisphosphinite ligand (R)-SpiroBIP has been synthesized. The rhodium complex of the ligand was found to be highly enantioselective in the asymmetric hydrogenation of α-dehydroamino acid derivatives.
- Guo, Zhenqiu,Guan, Xiaoyu,Chen, Zhiyong
-
p. 468 - 473
(2007/10/03)
-
- Electronic and steric effects of ligands as control elements for rhodium-catalyzed asymmetric hydrogenation
-
Chiral diphosphine ligands analogous to bdpp have been synthesized and tested in order to study the effect of the electronic nature of the ligands in Rh-catalyzed asymmetric hydrogenation of some prochiral olefins. The results are compared with those obtained with the analogous unsubstituted ligand (bdpp). The rhodium-catalyzed asymmetric hydrogenation of olefins was influenced by ligand-based electronic effects, as well as substrate based ones. Excellent ee's (up to 98.3%) have been obtained in the rhodium-catalyzed hydrogenation of (Z)-α-acetamidocinnamic acids and esters.
- Herseczki, Zsanett,Gergely, Ildiko,Hegedues, Csaba,Szoellosy, Aron,Bakos, Jozsef
-
p. 1673 - 1676
(2007/10/03)
-
- ASYMMETRIC SYNTHESIS CATALYZED BY TRANSITION METAL COMPLEXES WITH CYCLIC CHIRAL PHOSPHINE LIGANDS
-
The present invention relates to rigid chiral ligands usefull in making catalysts for asymmetric synthesis. More particularly, the present invention relates to new monodentate and bidentate cyclic chiral phosphine ligands which are formed into catalysts to provide high selectivity of the enantiomeric structure of the end-product.
- -
-
-
- Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
-
Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
- -
-
Page column 22
(2010/02/06)
-
- Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
-
Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
- -
-
Page column 22
(2010/01/30)
-
- Synthesis of chiral hydroxyl phospholanes from D-mannitol and their use in asymmetric catalytic reactions
-
Chiral hydroxyl monophosphane 3 [(2S,3S,4S,5S)-3,4-dihydroxy-2,5-dimethyl-1-phenylphospholane] and bisphospholanes 5a [1,2-bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-dimethylphospholanyl]benzene] and 5b [1,2-bis[(2S,3S,4S,5S)-2,5-diethyl-3,4-dihydroxyphospholanyl]benzene] were synthesized from readily available D-mannitol in high yields. Strategies for protection and deprotection of OH-groups in the presence of phosphines have been explored. Rate acceleration in the Baylis - Hillman reaction was observed when a hydroxyl phosphine was used as the catalyst. Rhodium complexes with chiral bisphospholanes are highly enantioselective catalysts for the asymmetric hydrogenation of various kinds of functionalized olefins such as dehydroamino acid derivatives, itaconic acid derivatives, and enamides. An interesting feature of the hydroxyl phospholane system is that hydrogenation of some substrates can be carried out in water with >99% ee and 100% conversion (e.g., itaconic acid).
- Li, Wenge,Zhang, Zhaoguo,Xiao, Dengming,Zhang, Xumu
-
p. 3489 - 3496
(2007/10/03)
-
- Rhodium-hydroxyl bisphospholane catalyzed highly enantioselective hydrogenation of dehydroamino acids and esters
-
A chiral hydroxyl bisphospholane, 1,2-bis[(2S,3S,4S,5S)-3,4-dihydroxyl-2,5-dimethylphospholanyl]benzene (4), was synthesized from readily available D-mannitol. Its Rh(I) complex catalyzes asymmetric hydrogenation of dehydroamino acids and their ester derivatives with excellent enantioselectivities (98 to >99% ee).
- Li, Wenge,Zhang, Zhaoguo,Xiao, Dengming,Zhang, Xumu
-
p. 6701 - 6704
(2007/10/03)
-
- Polymer-Supported Mitsunobu Ether Formation and its Use in Combinatorial Chemistry
-
Aromatic hydroxy acids have been attached to a polymeric solid support and the phenolic hydroxy groups have been reacted with a variety of primary and secondary alcohols under the conditions of the Mitsunobu reaction (triphenylphosphine and diethyl azodicarboxylate) in tetrahydrofuran.In most cases the reaction provided a nearly quantitative yield of alkyl aryl ethers, as determined after cleaving theproduct from the resin.To demonstrate that the polymer-supported Mitsunobu reaction is useful for combinatorial library synthesis, we synthesized a number of model compounds and a simple three randomization step library composed of 4,200 different compounds.
- Krchnak, Viktor,Flegelova, Zuzka,Weichsel, Aleksandra S.,Lebl, Michal
-
p. 6193 - 6196
(2007/10/02)
-
- Synthesis and application of (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran as ligand for asymmetric hydrogenation of acrylic acids
-
A new, chiral bisphosphine, (3R,4R)-3,4-bis(diphenylphosphino)tetrahydrofuran (4), is synthesized in three steps from (R,R)-tartaric acid esters. With rhodium(I) complexes of 4 enantiomeric excesses of 54 to 97% are obtained on catalytic hydrogenation of 2-(acetylamino)acrylic acid, 2-(acetylamino)cinnamic acids and itaconic acid. The applied substrate/catalyst ratios were between 250:1 and 11,000:1.
- Terfort
-
p. 951 - 953
(2007/10/02)
-
- Efficient Asymmetric Hydrogenations of (Z)-2-Acetamidoacrylic Acid Derivatives with the Cationic Rhodium Complex of (2S,4S)-MOD-BPPM
-
The preparation of (2S,4S)-MOD-BPPM ((2S,4S)-N-(t-butoxycarbonyl)-4-phosphino>-2-phosphino>methyl>pyrrolidine) and its application to highly effective asymmetric hydrogenations of (Z)-2-acetamidoacrylic acid derivatives are described.
- Takahashi, Hisashi,Achiwa, Kazuo
-
p. 305 - 308
(2007/10/02)
-
- Enantioselective Catalysis, 4. Synthesis of N-Substituted (R,R)-3,4-Bis(diphenylphosphino)pyrrolidines. The Use of their Rhodium Complexes for the Asymmetric Hydrogenation of α-(Acylamino)acrylic Acid Derivatives
-
A simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 6l and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue.The structure of the parent compound 6a was determined by X-ray diffraction.From the phosphanes 6a-m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-m were prepared.The complexes 7l and 7m are ligand bridged bis(rhodium) dications.The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the α-(acylamino)acrylic acid derivatives 9a-l.Enantiomeric excesses up to 100percent were achieved.Between 1 and 70 at the optical yields do not depend on the hydrogen pressure.The substrate/catalyst ratio can be as high as 50000/1.
- Nagel, Ulrich,Kinzel, Elke,Andrade, Juan,Prescher, Guenter
-
p. 3326 - 3343
(2007/10/02)
-
- Octapeptides and methods for their production
-
New octapeptides having the formula Prot Grp-R-Trp-Ser-Tyr-R2 -Leu-Arg-Pro-R3 ; salts thereof; wherein R is Gln, Gln (bzl), His (bzl), Ser (bzl), Pro, Leu, Tyr (bzl), Ile, Cys (bzl) or Phe, R2 is D-Phe, D-Ala, D-Leu, D-Trp, D-Tyr, D-Tyr (Me), D-Ser, D-Met, D-Arg, D-Val, D-His, D-Gln, D-Phs, D-Thr, D-Pro, D-Me5 Phe or D-Asn and R3 is NH2, NH(lower alkyl), N-(lower alkyl)2, NH-benzyl, NHCH2 CH2 N-(lower alkyl)2 or NH-CH2 CH2 SO2 NH-benzyl; methods for their production; certain peptide intermediates and their salts used in the production thereof; and the use of said octapeptides as luteinizing hormone releasing factor antagonists.
- -
-
-
- L-3-hydroxymethyltyrosine and salts thereof for lowering blood pressure
-
L-3-Hydroxymethyltyrosine and pharmaceutically acceptable salts thereof useful in lowering blood pressure and compositions thereof.
- -
-
-