- Synthesis and Biological Evaluation of CF3Se-Substituted α-Amino Acid Derivatives
-
Several CF3Se-substituted α-amino acid derivatives, such as (R)-2-amino-3-((trifluoromethyl)selanyl)propanoates (5 a/6 a), (S)-2-amino-4-((trifluoromethyl)selanyl)butanoates (5 b/6 b), (2R,3R)-2-amino-3-((trifluoromethyl)selanyl)butanoates (5 c/6 c), (R)-2-((S)-2-amino-3-phenylpropanamido)-3-((trifluoromethyl)selanyl)propanoates (11 a/12 a), and (R)-2-(2-aminoacetamido)-3-((trifluoromethyl)selanyl)propanoates (11 b/12 b), were readily synthesized from natural amino acids and [Me4N][SeCF3]. The primary in vitro cytotoxicity assays revealed that compounds 6 a, 11 a and 12 a were more effective cell growth inhibitors than the other tested CF3Se-substituted derivatives towards MCF-7, HCT116, and SK-OV-3 cells, with their IC50 values being less than 10 μM for MCF-7 and HCT116 cells. This study indicated the potentials of CF3Se moiety as a pharmaceutically relevant group in the design and synthesis of novel biologically active molecules.
- Han, Zhou-Zhou,Dong, Tao,Ming, Xiao-Xia,Kuang, Fu,Zhang, Cheng-Pan
-
p. 3177 - 3180
(2021/07/28)
-
- Synthesis and Conformational Analysis of Aminopyrazolonyl Amino Acid (APA)/Peptides
-
Pyrazole, pyrazolone, and aminopyrazolone derived molecules are bioactive molecules and considered as potential therapeutic drug candidates because of their unique structural properties. These molecules have abilities to interact with several bio-macromolecules via non-covalent interactions such as hydrogen bonding and π–π interactions. In structural organization of dipeptides, pyrazole containing aromatic amino acid/dipeptides have been explored and considered as potential amino acid residue. In repertoire of unnatural aromatic amino acids, this report describes the synthesis of 4-aminopyrazolonyl containing amino acids and their crystal structures. The incorporation of 4-aminopyrazolonyl at N-terminal of native amino acid/dipeptides influences the conformational changes of respective peptide which induces the formation of distinctive supramolecular self-assembly structures such as β-sheet and α-helices in their solid-state crystal. The structural conformation of those peptides, here, are also demonstrated in solution phase by 1H-NMR (1D/2D) and [D6]DMSO titration methods which support the formation of inter-/intramolecular hydrogen bonding in solution. Hence, these unnatural amino acid analogues can tune the secondary structure of natural amino acid/peptides by introducing at N-terminal via amide bond.
- Bollu, Amarnath,Sharma, Nagendra K.
-
supporting information
p. 1286 - 1292
(2019/02/01)
-
- Synthesis method of aztreonam monocyclic mother nucleus
-
The invention discloses a synthesis method of an aztreonam monocyclic mother nucleus, and mainly relates to the technical field of pharmaceutical and chemical industry. The method comprises the stepsthat L-threonine is subjected to methyl esterification; terbutyloxycarbonyl anhydride is used for performing amino BOC protection; ammonia water is subjected to ammonolysis; under the catalysis of a solid basic catalyst, methyl-sulfuric-acyl reaction and sulfonation are performed; cyclization, deprotection and acidification are performed to obtain the aztreonam monocyclic mother nucleus. The raw materials are cheap and can be easily obtained; the yield is high; the cost is low; the synthesis method belongs to a green, energy-saving and environment-friendly practical technology.
- -
-
Paragraph 0046; 0047
(2019/06/13)
-
- Serine- and threonine-derived diamine equivalents for site-specific incorporation of platinum centers in peptides, and the anticancer potential of these conjugates
-
A modular strategy that allows introduction of one or more reactive platinum units at chosen locations along a peptide sequence is presented. This makes use of diazides generated from serine and threonine as diamine equivalents which can be conjugated to the peptide under standard coupling conditions. Reduction of these diazides using Pd/C and H2 followed by platination affords the final products in good yields. Following this, we prepared a new class of peptide-platinum conjugates and carried out preliminary cytotoxicity evaluation and DNA interaction studies. Inclusion of lysine residues in the sequence was found to improve DNA interaction and anticancer activities compared to analogous conjugates with hydrophobic side chains.
- Kumbhakonam, Sateeshkumar,Vellaisamy, Kasipandi,Saroj, Soumya,Venkatesan, Nalini,Karunagaran,Manheri, Muraleedharan Kannoth
-
p. 2450 - 2458
(2018/02/19)
-
- Preparation method of O-methyl-threonine/tyrosine
-
The invention relates to a preparation method of O-methyl-threonine/tyrosine. The preparation method mainly overcomes the disadvantages of the existing method that a toxic reagent is volatile, the reagent is dangerous, the steps are long, the yield is low, and the like. The preparation method of the O-methyl-threonine/tyrosine comprises the following steps: N-t-butyloxycarboryl-threonine/tyrosineis catalyzed by sodium hydroxide and reacts with dimethyl sulfate to generate N-t-butyloxycarboryl-O-methyl-threonine/tyrosine, and then t-butyloxycarboryl is removed from the N-t-butyloxycarboryl-O-methyl-threonine/tyrosine through acid substances to obtain the product O-methyl-threonine/tyrosine. The product has important application in the fields of antibiotics and polypeptide drugs.
- -
-
Paragraph 0013
(2018/06/21)
-
- Hydroxy-Directed Amidation of Carboxylic Acid Esters Using a Tantalum Alkoxide Catalyst
-
We describe herein a new strategy for the chemoselective synthesis of amides by using a metal-catalyzed hydroxy-directed reaction. A hydroxy group located at the β-position of an ester group promoted the activation of a carbonyl group with a tantalum alkoxide catalyst followed by amidation reactions, leading to a wide variety of β-hydroxyamides with excellent chemeselectivity. The chemoselective amidation strategy can be extended to the catalytic synthesis of dipeptide derivatives, which remains challenging research subjects in modern organic synthesis.
- Tsuji, Hiroaki,Yamamoto, Hisashi
-
supporting information
p. 14218 - 14221
(2016/11/13)
-
- Oxidative deselenization of selenocysteine: Applications for programmed ligation at serine
-
Despite the unique chemical properties of selenocysteine (Sec), ligation at Sec is an under-utilized methodology for protein synthesis. We describe herein an unprecedented protocol for the conversion of Sec to serine (Ser) in a single, high-yielding step.
- Malins, Lara R.,Mitchell, Nicholas J.,McGowan, Sheena,Payne, Richard J.
-
supporting information
p. 12716 - 12721
(2015/10/28)
-
- Phosphine-catalyzed enantioselective γ-addition of 3-substituted oxindoles to 2,3-butadienoates and 2-butynoates: Use of prochiral nucleophiles
-
The first phosphine-catalyzed enantioselective γ-addition with prochiral nucleophiles and 2,3-butadienoates as the reaction partners has been developed. Both 3-alkyl- and 3-aryl-substituted oxindoles could be employed in this process, which is catalyzed by a chiral phosphine that is derived from an amino acid, thus affording oxindoles that bear an all-carbon quaternary center at the 3-position in high yields and excellent enantioselectivity. The synthetic value of these γ-addition products was demonstrated by the formal total synthesis of two natural products and by the preparation of biologically relevant molecules and structural scaffolds.
- Wang, Tianli,Yao, Weijun,Zhong, Fangrui,Pang, Guo Hao,Lu, Yixin
-
supporting information
p. 2964 - 2968
(2014/04/03)
-
- A 3,4-trans-fused cyclic protecting group facilitates α-selective catalytic synthesis of 2-deoxyglycosides
-
A practical approach has been developed to convert glucals and rhamnals into disaccharides or glycoconjugates with high α-selectivity and yields (77-97 %) using a trans-fused cyclic 3,4-O-disiloxane protecting group and TsOH·H2O (1 mol %) as a catalyst. Control of the anomeric selectivity arises from conformational locking of the intermediate oxacarbenium cation. Glucals outperform rhamnals because the C6 side-chain conformation augments the selectivity.
- Balmond, Edward I.,Benito-Alifonso, David,Coe, Diane M.,Alder, Roger W.,McGarrigle, Eoghan M.,Galan, M. Carmen
-
supporting information
p. 8190 - 8194
(2014/08/18)
-
- Intramolecular C-H...O hydrogen-bond mediated stabilization of a Cis- D Pro imide-bond in a stereocontrolled heterochiral model peptide
-
The X-ray diffraction analysis of a stereocontrolled heterochiral designed model peptide Boc-DPro-Thr-OMe (1) revealed the existence of an unusual folded molecular structure, stabilized via an effective unconventional C-H...O type intramolecular hydrogen-bond, encompassing a noncovalent 12-membered ring-motif. Together with an uncommon type a disposition of the urethane moiety, the tightly folded topology is compounded with a cis- DPro imide-bond. The overall conformation is suggested to be the reminiscent of specific type VI β-turn structures, hitherto, characterized across the Aaa-cis-Pro peptide-bonds in globular proteins and polypeptides. The 13C NMR spectrum of 1 in an apolar CDCl3 environment revealed the presence of approximately an equal population of cis and trans isomers unexpectedly, analogous to Pro side-chain, the 13C NMR chemical-shifts of Thr Cβ-resonance is observed to be sensitive toward cis-trans isomerization. In conjunction with solid-state FT-IR spectral data, we established that a network of complex intermolecular hydrogen-bonds stabilize a self-complementary noncovalent helical hexagonal self-assembly and crystallographic supramolecular aggregate. The results incline us to highlight that the stabilization of cis-DPro peptide-bond in crystalline state may be driven by the favorable energy of formation of an unconventional weak C-H...O intramolecular hydrogen-bond. Copyright
- Bhadbhade, Mohan M.,Kishore, Raghuvansh
-
experimental part
p. 73 - 82
(2012/08/08)
-
- Poly(vinyl)chloride supported palladium nanoparticles: Catalyst for rapid hydrogenation reactions
-
Palladium nanoparticles supported over poly(vinyl)chloride matrix (PVC-Pd0) are prepared through an efficient and inexpensive protocol. The catalyst has been characterized by XRD, SEM and TEM and its utility for the reduction of a range of functional groups as well as for the removal of some common protecting groups employed in peptide chemistry is demonstrated.
- Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
-
experimental part
p. 2597 - 2601
(2011/05/12)
-
- A practical strategy for the structural diversification of aliphatic scaffolds through the palladium-catalyzed picolinamide-directed remote functionalization of unactivated C(sp3)-H bonds
-
Hats off to the director: High levels of regio- and stereoselectivity were observed for a broad range of amine substrates with aryl and vinyl iodide coupling partners in the title reaction. The synthetic utility of this strategy was highlighted by the rea
- He, Gang,Chen, Gong
-
supporting information; experimental part
p. 5192 - 5196
(2011/06/26)
-
- Synthesis of the N-(tert-butyloxycarbonyl)-O-triisopropylsilyl-d- pyrrolosamine glycal of lomaiviticins A and B via epimerization of l-Threonine
-
An efficient synthesis of the N-(tert-butyloxycarbonyl)-O- triisopropylsilyl-d-pyrrolosamine glycal of lomaiviticin A (1) and lomaiviticin B (2) is described. The synthesis is highlighted by the epimerization of the l-threonine-derived oxazolidine 10 to oxazolidine 11. This key epimerization reaction, which serves to establish the correct relative configuration of the carbohydrate unit, was made possible only after conformational analysis indicated that substituted oxazolidines may adopt conformations that preclude enolization.
- Morris, William J.,Shair, Matthew D.
-
scheme or table
p. 4310 - 4312
(2010/09/20)
-
- An efficient synthesis of the tamandarin B macrocycle
-
A reliable, high yielding cyclization protocol for the macrocycle of tamandarin B is presented. This strategy will facilitate the synthesis of side chain analogs.
- Lassen, Kenneth M.,Lee, Jisun,Joullié, Madeleine M.
-
supporting information; experimental part
p. 1635 - 1638
(2010/06/14)
-
- Homophymine A, an anti-HIV cyclodepsipeptide from the sponge Homophymia sp.
-
(Chemical Equation Presented) A new anti-HIV cyclodepsipeptide, homophymine A, was isolated from a New Caledonian collection of the marine sponge Homophymia sp. The structure of homophymine A was determined by interpretation of spectroscopic data, acid hydrolysis, and LC-MS analysis. Homophymine A contains 11 amino acid residues and an amide-linked 3-hydroxy-2,4,6- trimethyloctanoic acid moiety. Along with four D-, two L-, and one N-methyl amino acids, it also contains four unusual amino acid residues: (2S,3S,4R)-3,4-diMe-Gln, (2R,3R,4S)-4-amino-2,3-dihydroxy-1,7-heptandioic acid, L-ThrOMe, and (2R,3R,4R)-2-amino-3-hydroxy-4,5-dimethylhexanoic acid. In a cell-based XTT assay, homophymine A exhibited cytoprotective activity against HIV-1 infection with a IC50 of 75 nM.
- Zampella, Angela,Sepe, Valentina,Luciano, Paolo,Bellotta, Filomena,Monti, Maria Chiara,D'Auria, Maria Valeria,Jepsen, Trine,Petek, Sylvain,Adeline, Marie-Therese,Laprevote, Olivier,Aubertin, Anne-Marie,Debitus, Cecile,Poupat, Christiane,Ahond, Alain
-
p. 5319 - 5327
(2008/12/22)
-
- An improved method for culturing Streptomyces sahachiroi: Biosynthetic origin of the enol fragment of azinomycin B
-
Azinomycin B is an environmental DNA crosslinking agent produced by the soil microorganism Streptomyces sahachiroi. While the agent displays potent cytotoxic activities against leukemic cell lines and animal mouse models, the lack of a consistent supply of the natural product has hampered detailed biological investigations on the compound, including its mode of action and biosynthesis. We report here a significant methodological improvement in the culturing of the bacterium, which allows reliable and steady production of the natural product in good yields. The key experimental step involves the culturing of the strain on dehydrated plates, followed by the generation of a two-stage starter culture and subsequent fermentation of the strain under nutrient-starved conditions. We illustrate use of this culture system by investigating the formation of the enol fragment of the molecule in isotopic labeling experiments with threonine and several advanced precursors (β-ketoamino acid 3, β-hydroxyamino aldehyde 4, and β-ketoaminoaldehyde 5). The results unequivocally show that threonine is the most advanced precursor accepted by the NRPS (non-ribosomal peptidyl synthetase) machinery for final processing and construction of the enol moiety of the natural product.
- Kelly, Gilbert T.,Sharma, Vasudha,Watanabe, Coran M.H.
-
-
- Olefin ring-closing metathesis as a powerful tool in drug discovery and development - potent macrocyclic inhibitors of the hepatitis C virus NS3 protease
-
Peptidomimetic inhibitors of the hepatitis C NS3 protease often exhibit poor biopharmaceutical properties. Structure modification of a substrate-based tripeptide into a β-strand 15-membered ring scaffold provided a new class of peptidomimetics that are si
- Tsantrizos, Youla S.,Ferland, Jean-Marie,McClory, Andrew,Poirier, Martin,Farina, Vittorio,Yee, Nathan K.,Wang, Xiao-jun,Haddad, Nizar,Wei, Xudong,Xu, Jinghua,Zhang, Li
-
p. 5163 - 5171
(2007/10/03)
-
- FIVE-MEMBERED HETEROCYCLIC DERIVATIVE
-
The present invention relates to a compound represented by formula (I): a salt of the compound, or a solvate of the compound or the salt; a drug containing any of the compounds, the salts, and the solvates; a preventive and/or therapeutic agent for an ischemic disease containing any of the compounds, the salts, and the solvates; and a platelet coagulation inhibitor containing any of the compounds, the salts, and the solvates. The compound of the present invention is useful as a strong platelet coagulation inhibitor without inhibiting COX-1 or COX-2.
- -
-
Page/Page column 25
(2010/11/08)
-
- A highly chemoselective Boc protection of amines using sulfonic-acid-functionalized silica as an efficient heterogeneous recyclable catalyst
-
A facile and versatile method for the chemoselective Boc protection of amines has been developed by a treatment with (Boc)2O in the presence of sulfonic-acid-functionalized silica as a catalyst. The method is general for the preparation of N-Boc derivatives of aliphatic (acyclic and cyclic), aromatic, and heteroaromatic amines; primary and secondary amines; aminols, amino-esters; and sulfonamides. The catalyst works under heterogeneous conditions and can be recycled.
- Das, Biswanath,Venkateswarlu, Katta,Krishnaiah, Maddeboina,Holla, Harish
-
p. 7551 - 7556
(2008/02/08)
-
- Macrocyclic hepatitis C serine protease inhibitors
-
The present invention relates to compounds of Formula I, II or Ill, or a pharmaceutically acceptable salt, ester, or prodrug, thereof: wherein W is a substituted or unsubstituted heterocyclic ring system. The compounds inhibit serine protease activity, particularly the activity of hepatitis c virus (HCV) NS3-NS4A protease. Consequently, the compounds of the present invention interfere with the life cycle of the hepatitis c virus and are also useful as antiviral agents. The present invention further relates to pharmaceutical compositions comprising the aforementioned compounds for administration to a subject suffering from HCV infection. The invention also relates to methods of treating an HCV infection in a subject by administering a pharmaceutical composition comprising the compounds of the present invention.
- -
-
Page/Page column 135
(2008/06/13)
-
- Quinoxalinyl macrocyclic hepatitis C serine protease inhibitors
-
The present invention relates to compounds of Formula I or II, or a pharmaceutically acceptable salt, ester, or prodrug, thereof: which inhibit serine protease activity, particularly the activity of hepatitis C virus (HCV) NS3-NS4A protease. Consequently, the compounds of the present invention interfere with the life cycle of the hepatitis C virus and are also useful as antiviral agents. The present invention further relates to pharmaceutical compositions comprising the aforementioned compounds for administration to a subject suffering from HCV infection. The invention also relates to methods of treating an HCV infection in a subject by administering a pharmaceutical composition comprising the compounds of the present invention.
- -
-
Page/Page column 53
(2008/06/13)
-
- An efficient procedure for the preparation of 4-substituted 5-aminoimidazoles
-
The preparation of O-methylimidates from α-aminonitriles and their subsequent co-cyclization with primary amines to afford 4-substituted 5-aminoimidazoles was studied. It was found that the mildly acidic pyridinium p-toluenesulfonate efficiently catalyzed each stage of the reaction sequence: (a) the formation of the O-methylimidates, (b) their co-cyclization with a variety of primary amines, and (c) certain derivatizations of the resultant heterocycles. The developed reaction conditions tolerate a wide variety of α-aminonitriles and primary amine co-reactants. Thus, it is possible to easily prepare a diverse array of substituted heterocyclic compounds in good yield. The requisite α-aminonitriles were synthesized either from amino acids or by phase-transfer alkylation of a glycine anion equivalent. The unstable free 5-aminoimidazoles were normally protected in situ to provide derivatives (methyl imidates or N,N-dimethylamidines) that were amenable to characterization.
- McLaughlin, Mark,Mohareb, Rafat M.,Rapoport, Henry
-
-
- The study of phosphoramidite as O-phosphitylation agent and its reactivity
-
O-phosphorylated peptide and amino acid are important in living system. In this paper, Dialkyl-N,N-dialkyl phosphoramidites (DDPA) 3 were synthesized using two methods. The reaction of DDPA with the hydroxyl group of the corresponding amino acids in the presence of tetrazole, followed by oxidation, gave O-phosphoryl amino acid methyl esters in a good yield. A systematical study of the reactivity of DDPA was presented too.
- Chen, Shui-Bing,Li, Yan-Mei,Luo, Shi-Zhong,Zhao, Gang,Tan, Bo,Zhao, Yu-Fen
-
p. 277 - 291
(2007/10/03)
-
- A New and Efficient Synthesis of Unnatural Amino Acids and Peptides by Selective 3,3-Dimethyldioxirane Side-Chain Oxidation
-
N-Boc derivatives of Leu, Met, Thr, Trp, and Pro, the properties of which resemble those of the respective α-amino acid residues present in proteins, rapidly oxidize in the presence of 3,3-dimethyldioxirane to give different products depending on the stru
- Saladino, Raffaele,Mezzetti, Maurizio,Mincione, Enrico,Torrini, Ines,Paradisi, Mario Paglialunga,Mastropietro, Gaia
-
p. 8468 - 8474
(2007/10/03)
-
- High yielding synthesis of dehydroamino acid and dehydropeptide derivatives
-
By using a 4-dimethylaminopyridine (DMAP) catalysed reaction of β-hydroxyamino acid derivatives with tert-butyl pyrocarbonate [(Boc)2O], dehydroamino acid derivatives are obtained in high yields. The same methodology applied to dipeptides with
- Ferreira, Paula M.T.,Maia, Hernani L.S.,Monteiro, Luis S.,Sacramento, Joana
-
p. 3697 - 3703
(2007/10/03)
-
- Total synthesis of (-)-muscoride A: A novel bis-oxazole based alkaloid from the cyanobacterium Nostoc muscorum
-
A convergent total synthesis of the substituted bis-oxazole (-)- muscoride A (1), isolated from a cyanobacterium, is described based on coupling of the N-functionalised 'reverse prenyl' dipeptide acid 8a to the threonine-based oxazole 9a, followed by elaboration of the tetrapeptide 7, via the oxazoline-oxazole 16 and the bis-oxazole ester 6.
- Muir,Pattenden,Thomas
-
p. 613 - 618
(2007/10/03)
-
- A new access to enantiomerically pure deoxy aminohexoses: Methyl 4-amino-4,6-dideoxy gulopyranoside and epi-tolyposamine
-
New efficient synthetic routes have been developed starting from the fully protected L-threonine derivative 1 for some deoxy-4-aminohexoses: methyl 4-amino-4,6-dideoxy gulopyranoside 2 and epi-tolyposamine 3. The title compounds were synthesized using an improved Horner-Emmons reaction of the threonine derived aldehyde 7. A new method for selective removal of the aminal protection is also reported.
- Koskinen, Ari M. P.,Otsomaa, Leena A.
-
p. 6473 - 6484
(2007/10/03)
-
- Dehydrooligopeptides. XVII. Practical syntheses of all of the diastereomers of N,N-protected 2,3-diaminobutanoic acids from L- and D-threonine derivatives
-
Syntheses of all of the dioctereomers of 2,3-diaminobutanoic acids, found in some pedtide antibiotics and toxins, were accomplished. The four isomers were derived mainly through two pathways including S(N)2 inversions of the β-substituent of L- or D-threonine derivatives. The various protecting groups and effective nucleophiles for the S(N)2 inversion were examined.
- Nakamura,Hirai,Tamotsu,Yonezawa,Shin
-
p. 1369 - 1377
(2007/10/02)
-
- Total synthesis of bleomycin A2 and related agents. 1. Synthesis and DNA binding properties of the extended C-terminus: Tripeptide S, tetrapeptide S, pentapeptide S, and related agents
-
Full details of concise, diastereocontrolled syntheses of 2-5 and their incorporation into tri-, tetra-, and pentapeptide S, the C-terminus of bleomycin A2, are described. The extension of the studies to the synthesis of a complete set of tri- and tetrapeptide S structural analogs 29a,b and 43b-j is detailed, and their DNA binding constants (apparent K(B), calf thymus DNA) and apparent binding site sizes were determined. Consistent with past observations, the studies highlight the fact that the majority of the DNA binding affinity for bleomycin A2 (1.0 X 105 M-1) and deglycobleomycin A2 (1.1 x 105 M-1) is embodied within N-BOC-tripeptide S (0.26 x 105 M-1). The additional comparisons of 29a (0.18 x 105 M-1), N-BOC-tetrapeptide S (0.21 x 105 M-1), 43h (0.20 x 105 M-1), and N-BOC pentapeptide S (0.23 x 105 M-1) versus N-BOC-dipeptide S (0.10 x 105 M-1) indicate productive stabilizing binding interactions for the tripeptide S L-threonine subunit and substituent, illustrate that the entire pentanoic acid subunit of tetrapeptide S and its substituents do not significantly contribute to DNA binding affinity, and indicate that the entire β-hydroxy-L-histidine subunit of pentapeptides does not contribute to DNA binding affinity. With the exception of the L-threonine side chain substituent, the observations suggest that the tri- and tetrapeptide S substituent effects on the bleomycin A2 DNA cleavage reaction are not due to substantial stabilizing binding interactions with duplex DNA. In addition, the measured apparent binding site sizes for bleomycin A2 (3.8 base pairs), deglycobleomycin A2 (3.9 base pairs), N-BOC-tripeptide S (3.6 base pairs), N-BOC-tetrapeptide S (3.7 base pairs), 43h (3.5 base pairs), and N-BOC-pentapeptides (4.2 base pairs) versus N-BOC-dipeptide S (2.2 base pairs) and 29a (2.7 base pairs) suggest that it is the tripeptide S subunit of bleomycin A2 that is fully bound to duplex DNA, that the tripeptide S L-threonine hydroxyethyl substituent detectably affects the agent interaction with duplex DNA, but that the presence or absence of the other tetrapeptide S and pentapeptide S backbone substituents do not substantially alter the binding site size or tripeptide S binding mode.
- Boger, Dale L.,Colletti, Steven L.,Honda, Takeshi,Menezes, Royce F.
-
p. 5607 - 5618
(2007/10/02)
-
- SIMPLE HETEROCYCLE, 2-OXAZOLONE, AS VERSATILE BUILDING BLOCK FOR 2-AMINO ALCOHOLS. CHIRAL SYNTHESIS OF POLYHALOTHREONINES
-
Smooth radical-initiated addition of CCl4 and CCl3Br to 3--2-oxazolone gives a 1:1 mixture of readily separable (4S,5R)- and (4R,5S)-4-halogeno-5-trichloromethyl-2-oxazolidinone derivatives, which serve for facile preparation of polychlorothreonines including 4,4-dichloro-2-amino-3-hydroxybutyric acid, known as antimicrobial armentomycin analog.
- Ishizuka, Tadao,Osaki, Mitsuyasu,Ishihara, Hideharu,Kunieda, Takehisa
-
p. 901 - 908
(2007/10/02)
-
- One-Pot Transformation of Benzyl Carbamates into t-Butyl Carbamates
-
An N-Cbz group is transformed into an N-Boc group in a single step by transfer hydrogenation in the presence of Boc2O.Functional groups such as Bn, BOM and TBDMS ethers are stable under the reaction conditions. Key Words: Transformation; benzyl carbamate;
- Bajwa, Joginder S.
-
p. 2955 - 2956
(2007/10/02)
-
- Synthesis of Tri- and Tetrapeptide S: The Extended C-Terminus of Bleomycin A2
-
Concise diastereocontrolled syntheses of tri- and tetrapeptide S, key subunits of the antitumor antibiotic bleomycin A2, are detailed.
- Boger, Dale L.,Menezes, Royce F.
-
p. 4331 - 4333
(2007/10/02)
-
- MILD AND SELECTIVE RING-CLEAVAGE OF CYCLIC CARBAMATES TO AMINO ALCOHOLS
-
N-tert-Butoxycarbonylated 2-oxazolidinones and tetrahydro-2-oxazinones are smoothly cleaved to acyclic N-Boc-amino alcohols on treatment with catalytic amounts of cesium carbonate at room temperature.The versatility of the procedure is demonstrated in a facile cleavage of highly functionalized heterocycles without epimerization and β-elimination.
- Ishizuka, Tadao,Kunieda, Takehisa
-
p. 4185 - 4188
(2007/10/02)
-
- The Synthesis and Configurational Stability of Differentially Protected β-Hydroxy-β-amino Aldehydes
-
Syntheses of 1,1-dimethylethyl (S)-4-formyl-2,2-dimethyl-3-oxazolidinecarboxylate (5) and 1,1-dimethylethyl (4S-trans)-4-formyl-2,2,5-trimethyl-3-oxazolidinecarboxylate (6) from commercially available serine and threonine derivatives are described.The method involves selective reduction of the corresponding oxazolidine esters 3 and 4 using diisobutylaluminum hydride at low temperature.These differentially protected β-hydroxy-α-amino aldehydes are also shown to be produced in 93-95 percent enantiomeric excess (via NMR and HPLC analysis of the Mosher esterderivatives 8 and epi-8)-thus making them useful as chiral, nonracemic synthons for asymmetric synthesis.
- Garner, Philip,Park, Jung Min
-
p. 2361 - 2364
(2007/10/02)
-
- Asymmetric Hydrogenation Catalyzed by Rhodium Complex with a New Chiral Bisphosphine Derived from L-Threonine
-
A new chiral bisphosphine, (2R,3S)-1,2-bis(diphenylphosphino)-3-'Boc-aminobutane (RS-5), was prepared from L-threonine.Mesylation of 'Boc-L-threonine methyl ester (2) and subsequent reduction with sodium borohydride gave the alcohol (10), which was treated with potassium carbonate to afford a key intermediate, (2S,3S)-1-'Boc-3-methyl-2-aziridinemethanol (SS-7b).Mesylation of SS-7b, followed by treatment with sodium diphenylphosphide afforded the new chiral bisphosphine (RS-5).The structure of RS-5 was confirmed by the X-ray analysis of its crystalline CuCl complex (RS-12).The cationic rhodium (I) complexes prepared from RS-5 and RS-12 are efficient asymmetric hydrogenation catalysts for N-acyldehydroamino acids, giving (S))-N-acylamino acids in high optical yields (83-94percentee).
- Saito, Kunio,Saijo, Shigeyoshi,Kotera, Keishi,Date, Tadamasa
-
p. 1342 - 1350
(2007/10/02)
-
