- SN2 displacement at the quaternary carbon center: A novel entry to the synthesis of α,α-disubstituted α-amino acids This Letter is dedicated to the late Professor Harry Wasserman, a great chemist as well as a splendid artist
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A novel method for the SN2 reaction on quaternary carbon atoms using bis(p-nitrophenyl)phosphorazidate has been developed. Chiral tertiary alcohols were directly converted into the corresponding chiral tertiary azides with complete inversion of configuration. Several α,α-disubstituted α-amino esters or amino acids were prepared through the conversion of azides to the corresponding amines by catalytic hydrogenation.
- Ishihara, Kotaro,Hamamoto, Hiromi,Matsugi, Masato,Shioiri, Takayuki
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supporting information
p. 3169 - 3171
(2015/05/27)
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- Synthesis and Anticonvulsant Activity of Substituted-1,3-diazaspiro[4.5]decan-4-ones
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A series of novel spiroimidazolidinone derivatives 6a-d and 8a-x were synthesized and biologically evaluated for their anticonvulsant activity in the maximal electroshock seizure (MES) assay and the subcutaneous pentylenetetrazole (scPTZ) screening test. Compound 8w was the most active derivative in the scPTZ screening test with an ED50 value by about 5- and 83.6-fold lower than those of phenobarbital and ethosuximide as reference drugs, respectively. Most of the tested compounds exhibited moderate to weak activity in the MES screen test, except for 8a which displayed 100% protection at 0.09 mmol/kg. Moreover, all the test compounds did not show any minimal motor impairment in the neurotoxicity test.
- Aboul-Enein, Mohamed Nabil,El-Azzouny, Aida Abdel Sattar,Saleh, Ola Ahmed,Amin, Kamilia Mahmoud,Maklad, Yousreya Ali,Hassan, Rasha Mohamed
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p. 575 - 588
(2015/08/11)
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- Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group
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In order to deprotect N-carbobenzoxy-l-aminoacids (Cbz-AA) and related compounds, a series of microorganisms was selected from soil by enrichment cultures with Cbz-l-Glu as sole nitrogen source. A lyophilized whole-cell preparation of two Arthrobacter sp. strains grown on Cbz-Glu or Cbz-Gly exhibited a high cleavage activity. The conditions of hydrolysis have been optimized and a quantitative enantioselective deprotection of several Cbz-dl-amino acids was obtained, as well as the deprotection of N-carbamoylester derivatives of several synthetic amino compounds. The preparation of Cbz-d-allylglycine and l-allylglycine in high yield and high optical purity is described as an application of this method.
- Maurs, Michele,Acher, Francine,Azerad, Robert
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- Two methods for spirothiohydantoin synthesis
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Two methods for spirothiohydantoin synthesis are presented. The title compounds were prepared with reaction of the corresponding 1- aminocycloalkanecarboxylic acids and thiourea. These compounds were also prepared by a hydrolysis of the relevant spirodithiohydantoins with barium hydroxide. The structures of the compounds obtained were verified by comparison of 1H, and 13C NMR, IR and MS spectral data.
- Stoyanov, Neyko,Marinov, Marin
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p. 680 - 685,6
(2020/08/24)
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- Microwave-assisted synthesis of cycloalkanespirohydantoins and piperidinespirohydantoins as precursors of restricted α-amino acids
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Cycloalkanespirohydantoins 3 and piperidinespirohydantoins 4 were synthesized from cycloalkanones 9 and piperidones 10 under microwave-assisted conditions. Results are compared with those obtained under thermal conditions. Cycloalkanespirohydantoins 3 were N-protected with Boc group and hydrolyzed under basic conditions to obtain five, six and seven-membered ring restricted α-amino acids 12 in very good overall yields (76-94%). ARKAT USA, Inc.
- Rivero, Ignacio A.,Reynoso-Soto, Edgar A.,Ochoa-Teran, Adrian
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experimental part
p. 260 - 271
(2011/05/13)
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- PEPTIDES AND PEPTIDOMIMETIC COMPOUNDS, THE MANUFACTURING THEREOF AS WELL AS THEIR USE FOR PREPARING A THERAPEUTICALLY AND/OR PREVENTIVELY ACTIVE PHARMACEUTICAL COMPOSITION
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Peptides, peptidomimetics and derivatives thereof of the general formula I: H2N-GHRPX1-β-X4X5X6X7X8X9X10-X11 (I), in which X1-X10 denote one of the 20 genetically coded amino acids, wherein X8, X9 and X10 may also denote a single chemical bond;X11 denotes OR1 in which R1 equals hydrogen or (C1-C10) alkyl NR2R3 with R2 and R3 are equal or different and denote hydrogen, (C1-C10) alkyl, or a residue —W-PEG5-60K, in which the PEG residue is attached via a suitable spacer W to the N-atom, ora residue NH—Y-Z-PEG5-60K, in whichY denotes a chemical bond or a genetically coded amino acids from the group S, C, K or R andZ denotes a spacer, via which a polyethylene glycol (PEG)-residue can be attached, and their physiologically acceptable salts, andβ denotes an amino acid, or a peptidomimetic element, which induces a bend or turn in the peptide backbone.
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- Versatile synthesis of free and N-benzyloxycarbonyl-protected 2,2-disubstituted taurines
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An effective and versatile method was developed to synthesize N-benzyloxycarbonyl-protected and free 2,2-disubstituted taurines. Several novel 2,2-disubstituted taurines, including aliphatic/aromatic and cyclic/acyclic derivatives, were obtained, which demonstrates the generality of this method. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Wang, Boyuan,Zhang, Wei,Zhang, Leilei,Du, Da-Ming,Liu, Gang,Xu, Jiaxi
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p. 350 - 355
(2008/09/18)
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- Novel N-(phosphonomethyl) glycine derivatives: Design, characterization and biological activity
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A series of Cα,α-disubstituted cyclic derivatives of N-(phosphonomethyl) glycine have been synthesized and characterized. They exhibited moderate clastogenicity, low antiproliferative activity on mice bone marrow cells and well expressed cytotoxicity against human tumor cell lines. The 8- and 12-membered cyclic analogs proved superior to the remaining compounds and were found to trigger apoptotic cell death in DOHH-2 cells. The latter compound caused 50% inhibition of the viability of hemobastose-derived cell lines at concentrations ranging from 20 to 67 μM.
- Naydenova, Emilia D.,Todorov, Petar T.,Topashka-Ancheva, Margarita N.,Momekov, Georgi Ts.,Yordanova, Tsvetelina Z.,Konstantinov, Spiro M.,Troev, Kolio D.
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p. 1199 - 1205
(2008/09/20)
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- Processes for producing alpha -aminonitrile derivatives and alpha -amino acids
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In the presence of a metal catalyst such as a samarium compound, an oxime ester compound shown by the formula (1): wherein R1, R2, and R3 are the same or different from each other, and each represents a non-reactive atom or a non-reactive organic group; and R2 and R3, together with the adjacent carbon atom, may bond together to form a ring is reacted with a cyanogenation agent such as an alpha -cyanohydrin compound (e.g., acetone cyanohydrin) to form an alpha -aminonitrile derivative. By hydrolyzing the alpha -aminonitrile derivative, the corresponding alpha -amino acid or a salt thereof can be obtained. According to the above processes, an alpha -aminonitrile derivative and an alpha -amino acid can be obtained in high yields.
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- Synthesis and tumorinhibiting activity of lanthanum(III) complexes with some 1-aminocycloalkancarboxylic acids
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Complexes of La(III) with 1-aminocyclopentane-, -hexane, -heptane and -4-ethylcyclohexanecarboxylic acids were obtained. The compounds were characterized by elemental analyses, IR spectroscopy and conductivity measurements. The following general formula was derived: LaL3Cl3·5 H2O, where L is the corresponding 1-aminocycloalkanecarboxylic acid. The pharmacological studies showed that all complexes manifested higher cytostatic and cytotoxic effects in comparison with lanthanum chloride. Much higher cytotoxic (anti-P388/D1) and cytostatic (anti-L-1210 and antimelanoma-B16) activity was found for the lanthanum complex with 1-aminocyclopentanecarboxylic acid.
- Kovachev,Ivanov,Buyukliev,Konstantinov,Karaivanova
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- Peptide Sweeteners. 6. Structural Studies on the C-Terminal Amino Acid of L-Aspartyl Dipeptide Sweeteners
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Stereochemical and structural aspects of the variations in the C-terminal residue of L-aspartyl-L-phenylalanine methyl ester have been investigated.Novel configurational analogues such as L-aspartyl-D-alanine benzyl ester and L-aspartyl-D-α-aminobutyric acid benzyl ester were found to be sweet.In addition, chiral and achiral α,α-dialkylglycine and α-aminocycloalkanecarboxylic acids were incorporated into the dipeptides.The L-aspartic acid based dipeptide derivatives of α-aminoisobutyric acid methyl ester, α-aminocyclopropanecarboxylic acid methyl ester, α-aminocyclobutanecarboxylic acid methyl ester, and α-aminocyclopentanecarboxylic acid methyl ester are sweet.Dipeptides with α-aminocyclohexanecarboxylic acid methyl ester and α-aminocycloheptanecarboxylic acid methyl ester are bitter, whereas the analogues with α-aminocyclooctanecarboxylic acid methyl ester, α,α-diethylglycine methyl ester, and α-aminoisobutyric acid benzyl ester are tasteless.Aspects on chirality and effective volume of the C-terminal residue are discussed and correlated with taste.
- Tsang, Joseph W.,Schmied, Bernhard,Nyfeler, Rolf,Goodman, Murray
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p. 1663 - 1668
(2007/10/02)
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- Platinum complex
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New platinum complex represented by the general formula [I]: STR1 wherein R1 and R2 are same and represent halogen atom or NO3, or R1 is SO4 and R2 is H2 O, or R1 and R2 are bonded with each other to form either STR2 and the configuration of 1-aminomethyl-2-aminocyclohexane is selected from trans-1, trans-d, cis-1 and cis-d. The compounds of the formula [I] are active against tumor and are expected to be useful as medicaments.
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