- Asymmetric Synthesis of the Diasteroisomers of L-1-Indanylglycine and L-1-Benzindanylglycine, χ1,χ2-Constrained Side-Chain Derivatives of L-Phenylalanine and L-2-Naphthylalanine
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The diastereoisomers of L-1-indanylglycine and L-1-benzindanylglycine, novel topographic tools and analogues of phenylalanine and 2-naphthylalanine, were synthesized from a sultam-derived glycine imine synthon alkylated by judicious electrophiles, and subsequent hydrolysis and sultam-cleavage.An X-ray analysis on one alkylation product established the β-configuration.Key Words: side-chain constrained α amino acids; L-1-indanylglycines; L-1-benzindanylglycines.
- Josien, Hubert,Chassaing, Gerard
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- Gas phase formation of cyclopentanaphthalene (benzindene) isomers: Via reactions of 5- And 6-indenyl radicals with vinylacetylene
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The tricyclic polycyclic aromatic hydrocarbons (PAHs) 3H-cyclopenta[a]naphthalene (C13H10), 1H-cyclopenta[b]naphthalene (C13H10) and 1H-cyclopenta[a]naphthalene (C13H10) along with their indene-based bicyclic isomers (E)-5-(but-1-en-3-yn-1-yl)-1H-indene, (E)-6-(but-1-en-3-yn-1-yl)-1H-indene, 5-(but-3-ene-1-yn-1-yl)-1H-in-dene, and 6-(but-3-ene-1-yn-1-yl)-1H-indene were formed via a directed synthesis in a high-temperature chemical micro reactor at the temperature of 1300 ± 10 K through the reactions of the 5- and 6-indenyl radicals (C9H7) with vinylacetylene (C4H4). The isomer distributions were probed utilizing tunable vacuum ultraviolet light by recording the photoionization efficiency curves at mass-to-charge of m/z = 166 (C13H10) and 167 (13CC12H10) of the products in a supersonic molecular beam. The underlying reaction mechanisms involve the initial formation of van-der-Waals complexes followed by addition of the 5- and 6-indenyl radicals to vinylacetylene via submerged barriers, followed by isomerization (hydrogen shifts, ring closures), and termination via atomic hydrogen elimination accompanied by aromatization. All the barriers involved in the formation of 3H-cyclopenta[a]naphthalene, 1H-cyclopenta[b]naphthalene and 1H-cyclopenta[a]naphthalene are submerged with respect to the reactants indicating that the mechanisms are in fact barrierless, potentially forming PAHs via the hydrogen abstraction-vinylacetylene addition (HAVA) pathway in the cold molecular clouds such as Taurus Molecular Cloud-1 (TMC-1) at temperatures as low as 10 K. This journal is
- Ahmed, Musahid,Azyazov, Valeriy N.,Bashkirov, Eugene K.,Evseev, Mikhail M.,Howlader, A. Hasan,Kaiser, Ralf I.,Kostko, Oleg,Lu, Wenchao,Mebel, Alexander M.,Oleinikov, Artem D.,Wnuk, Stanislaw F.,Zhao, Long
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p. 22493 - 22500
(2020/11/09)
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- Copper-Catalyzed Enantioselective Domino Arylation/Semipinacol Rearrangement of Allylic Alcohols with Diaryliodonium Salts
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A copper-catalyzed enantioselective arylative semipinacol rearrangement of allylic alcohols was developed. In the presence of a catalytic amount of an in situ generated chiral copper-bisoxazoline complex, reaction of allylic alcohols with diaryliodonium salts afforded spirocycloalkanones in high yields with high diastereo- and enantioselectivities. A two-point binding model engaging the carbon–carbon double bond and the proximal hydroxyl group was proposed to be responsible for the highly efficient chirality transfer.
- Wu, Hua,Wang, Qian,Zhu, Jieping
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p. 13037 - 13041
(2017/09/26)
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- Twisted baskets
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A preparative procedure for obtaining a pair of twisted molecular baskets, each comprising a chiral framework with either right ((P)-1syn) or left ((M)-1syn) sense of twist and six ester groups at the rim has been developed and optim
- Hermann, Keith,Pratumyot, Yaowalak,Polen, Shane,Hardin, Alex M.,Dalkilic, Erdin,Dastan, Arif,Badji?, Jovica D.
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supporting information
p. 3550 - 3555
(2015/03/04)
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- Synthesis and use of amino acid fluorides as peptide coupling reagents
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The present invention is directed to the process of preparing a peptide comprising reacting a first amino acid or peptide with an amino acid fluoride of the formula: STR1 or the acid fluoride salts thereof wherein BLK is an N-amino protecting group AA is an amino acid residue and X is H or a protecting group useful, and the first amino and peptide have a free amino group and a blocked carboxy end.
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- A convenient synthesis of Benz[f]Indene
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The crucial annulation of sulfone aldehyde 2 with enone 3 has led to an operationally simple two-step synthesis of benz[f]indene1, and its derivatives 8 and 9 involving a new rearrangement.
- Ghorai, Sujit K.,Hazra, Nirmal K.,Mal, Dipakranjan
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p. 689 - 690
(2007/10/03)
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- Synthesis and use of amino acid fluorides as peptide coupling reagents
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A compound of the formula STR1 or the acid fluoride salts thereof wherein BLK is an N-amino protecting group or hydrogenAA is an amino acid residue andX is H or a protecting group useful as a coupling agent in peptide synthesis.
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- Design and Synthesis of Side-Chain Conformationally Restricted Phenylalanines and Their Use for Structure-Activity Studies on Tachykinin NK-1 Receptor
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Constrained analogues of phenylalanine have been conceptually designed for analyzing the binding pockets of Phe7 (S7) and Phe8 (S8), two aromatic residues important for the pharmacological properties of SP, i.e., L-tetrahydroisoquinoleic acid, L-diphenylalanine, L-9-fluorenylglycine (Flg), 2-indanylglycine, the diastreomers of L-1-indanylglycine (Ing) and L-1-benzindanylglycine (Bfi), and the Z and E isomers of dehydrophenylalanine (ΔZPhe, ΔEPhe).Binding studies were performed with appropriate ligands and tissue preparations allowing the discrimination of the three tachykinin binding sites, NK-1, NK-2, and NK-3.The potencies of these agonists were evaluated in the guinea pig ileum bioassay.According to the binding data, we can conclude that the S7 subsite is small, only the gauche(-) probe 7>SP presents a high affinity for specific NK-1 binding sites.Surprisingly, the EPhe7>SP analogue, which projects the aromatic ring toward the trans orientation, is over 40-fold more potent than the Z isomer, ZPhe7>SP.A plausible explanation of these conflictual results is that either the binding protein quenches the minor trans rotamer of 7>SP in solution or this constrained amino acid side chain rotates when inserted in the protein.In position 8, the high binding affinities of 8>SP and 8>SP suggest that the S8 subsite is large enough to accept two aromatic rings in the gauche(-) and one aromatic ring in the trans direction.Peptides bearing two conformational probes in positions 7, 8 or 9 led to postulate that S7, S8, and S9 subsites are independent from each other.The volumes available for side chains 7 and 8 can be estimated to be close to 110 and 240 Angstroem3, respectively.The large volume of the S8 subsite raises question on the localization of the SP-binding site in the NK-1 receptor.If SP were to bind in the transmembrane domains, the cleft defined by the seven transmembrane segments must rearrange during the binding process in order to bind a peptide in an α-helical structure and at least one large binding subsite in position 8.Thus, indirect topographical analysis with constrained amino acids might contribute to the analysis of the receptor/ligand dynamics.Finally, this study demonstrates that a good knowledge of the peptidic backbone structure and a combination of constrained amino acids are prerequisites to confidently attribute the preferred orientation(s) of an amino acid side chain.
- Josien, Hubert,Lavielle, Solange,Brunissen, Alie,Saffroy, Monique,Torrens, Yvette,et al.
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p. 1586 - 1601
(2007/10/02)
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- Benzindene
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A convenient route to benzindene (1) has been developed in which 2-methylnaphthalene is brominated sequentially in the α-position and the methyl group followed by application of a standard malonic ester route to propionic acid 10.Cyclization of 10 via the acid chloride gave 11 (76percent).Simultaneous reduction of the carbonyl group and hydrogenolysis of the aryl bromide linkage of 11 gave secondary alcohol 12 in 55.4percent yield.Sulfuric acid dehydration of 12 gave 1 (85percent).Less successful routes to 1 involved dithionite reduction of unsaturated sulfones 6.Dihydro derivative 7 could be synthesized in 72percent yield by magnesium/methanol reduction of 5b.
- Carpino, Louis A.,Lin, Yao-Zhong
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p. 247 - 250
(2007/10/02)
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- BENZINDENE AND ITS KATZ REACTION
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A novel and very short synthesis of the useful title hydrocarbon 2 is presented.Its key step is based on a Diels-Alder reaction of isobenzofuran 4.The lithium salt of 2 gives a remarkably stable valence isomer of anthracene 1 in a reaction analogous to the indene -> benzobenzvalene transformation.
- Burger, Ulrich,Thorel, Pierre-Jean,Schaller, Jean-Pierre
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p. 3155 - 3156
(2007/10/02)
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