cas 45170-31-8, Boc-N-methyl-L-valine | Articles data

Articles about 45170-31-8Total 54 be found

Article title
Article abstract
Author
Journal number and time
Download

Synthetic studies on quinoxaline antibiotics: II. Synthesis of triostin A
Triostin A, a cyclic octadepsipeptide, was synthesized with Z-D-Ser[Boc-Ala-MeCys(Bzl)-MeVal]-OH and Z-n-Ser[H-Ala-MeCys(Bzl)-MeVal]-OTce as key intermediates. The synthetic antibiotic was compared with natural triostin A in terms of chromatographic behaviors, NMR spectra, and antomicrobial activity to establish their identity. The NMR data on S,S'-dibenzyldihydrotriostin A showed that this intermediate lacking the disulfide linkage also existed as two conformers in chloroform. This observation excludes the possibility that the conformer equilibrium known to occur with triostin A is a consequence of the reversed chirality of the disulfide bond. Triostin A, a cyclic octadepsipeptide, was synthesized with Z-D-Ser left bracket Boc-Ala-MeCys(Bzl)-MeVal right bracket -OH and Z- D-Ser left bracket H-Ala-MeCys(Bzl)-MeVal right bracket -OTce as key intermediates. The synthetic antibiotic was compared with natural triostin A in terms of chromatographic behaviors, NMR spectra, and antimicrobial activity to establish their identity. The NMR data on S,S prime -dibenzyldihydrotriostin A showed that this intermediate lacking the disulfide linkage also existed as two conformers in chloroform. This observation excludes the possibility that the conformer equilibrium known to occur with triostin A is a consequence of the reversed chirality of the disulfide bond.
Shin,Otsuka
p. 2203 - 2210
(1984)
Read Online

NOVEL CONNECTED BODY AND USE THEREOF IN SPECIFIC CONJUGATION BETWEEN BIOMOLECULE AND DRUG
PROBLEM TO BE SOLVED: To provide: a method for producing a connected body; a method for using the connected body in the production of a uniform conjugate; and a method for applying the conjugate in the treatment of cancer, infectious diseases, and autoimmune diseases. SOLUTION: A novel connected body is provided that includes a 2,3-di-substituted succinic acid group or a 2-mono-substituted or 2,3-di-substituted fumaric acid or maleic acid (trans (E)- or cis (Z)-butenedioic acid) group for conjugating 2 or more compounds/cytotoxic agents per connected body with a cell-binding molecule by specifically bridge-linking to a pair of thiol on the cell-binding molecule. The connected body is exemplified by the following general formula. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
-
Paragraph 0260-0261

(2021/05/14)

Isolation and Total Synthesis of Kinenzoline, an Antitrypanosomal Linear Depsipeptide Isolated from a Marine Salileptolyngbya sp. Cyanobacterium
Kinenzoline (1), a new linear depsipeptide, was isolated from a marine Salileptolyngbya sp. cyanobacterium. Its structure was elucidated by spectroscopic analyses and degradation reactions. In addition, we achieved a total synthesis of 1 and confirmed its structure. Kinenzoline (1) showed highly selective antiproliferative activity against the causative organism of sleeping sickness, Trypanosoma brucei rhodesiense (IC50 4.5 μM), compared to normal human cells (WI-38, IC50 > 100 μM). Kinenzoline (1) is a promising lead compound for the development of new antitrypanosomal drugs.
Kurisawa, Naoaki,Otomo, Keisuke,Iwasaki, Arihiro,Jeelani, Ghulam,Nozaki, Tomoyoshi,Suenaga, Kiyotake
p. 12528 - 12536
(2021/09/20)

First total synthesis of hoshinoamide A
Hoshinoamides A, B and C, linear lipopeptides, were isolated from the marine cyanobacterium Caldora penicillata, with potent antiplasmodial activity against chloroquine-sensitive Plasmodium falciparum. Herein, we describe the first total synthesis of hosh
Liu, Long,Rui, Zihan,Shao, Yutian,Xu, Shengtao,Yang, Yiming,Zhou, Haipin
supporting information
p. 2924 - 2931
(2022/01/12)

CONJUGATION LINKERS CONTAINING 2,3-DIAMINOSUCCINYL GROUP
Provided is a conjugate of a cytotoxic drug/molecule to a cell-binding molecule with a bis-linker (adual-linker) containing a 2, 3-diaminosuccinyl group. It also relates to preparation of the conjugate of a cytotoxic drug/molecule to a cell-binding molecule with the bis-linker, particularly when the drug having functional groups of amino, hydroxyl, diamino, amino-hydroxyl, dihydroxyl, carboxyl, hydrazine, aldehyde and thiol for conjugation with the bis-linker in a specific manner, as well as the therapeutic use of the conjugates.
-
Page/Page column 210

(2020/05/19)

Benzoazepine-Fused Isoindolines via Intramolecular (3 + 2)-Cycloadditions of Azomethine Ylides with Dinitroarenes
Aminobenzaldehydes bearing a pendant 3,5-dinitrophenyl group react thermally with N-substituted α-amino acids to form unprecedented benzoazepine-fused isoindolines. The reaction proceeds via a dearomatization/rearomatization sequence involving an intramolecular (3 + 2)-cycloaddition between the in situ formed azomethine ylide and the dinitroarene. Various glycine derivatives are tolerated as well as branched substrates based on cyclic, α-mono-, and α,α-disubstituted amino acids, giving single diastereomers in many cases. The method is scalable and gives products with a nitro group ready for further manipulation.
Wales, Steven M.,Rivinoja, Daniel J.,Gardiner, Michael G.,Bird, Melissa J.,Meyer, Adam G.,Ryan, John H.,Hyland, Christopher J. T.
supporting information
p. 4703 - 4708
(2019/06/27)

CONJUGATION OF A CYTOTOXIC DRUG WITH BIS-LINKAGE
What provided is the conjugation of cytotoxic to a cell-binding molecule with a bis-linker(dual-linker) as shown in Formula (I). It provides bis-linkage methods of making a conjugate of a cytotoxic drug molecule to a cell-binding agent in a specific manner. It also relates to application of the conjugates for the treatment of a cancer, or an autoimmune disease, or an infectious disease.
-
Paragraph 0717-0719

(2020/01/08)

Synthesis of Majusculamides A and B
The synthesis of two marine lipodipeptides, majusculamides A and B, is described. The key feature of this synthesis is the stereoselective construction of an α-methyl-β-keto-carboxamide moiety.
Nakajima, Daisuke,Sueyoshi, Kosuke,Orihara, Kensuke,Teruya, Toshiaki,Yokoshima, Satoshi
supporting information
p. 924 - 927
(2019/05/10)

CONJUGATION LINKERS, CELL BINDING MOLECULE-DRUG CONJUGATES CONTAINING THE LIKERS, METHODS OF MAKING AND USES SUCH CONJUGATES WITH THE LINKERS
The present invention relates to linkers having a group of propiolyl, substituted acryl (acryloyl), or disubstituted propanoyl, and using such linkers for the conjugation of compounds, in particular, cytotoxic agents to a cell-binding molecule.
-
Page/Page column 164

(2018/05/27)

CONJUGATE OF MONOMETHYL AURISTATIN F AND TRASTUZUMAB AND ITS USE FOR THE TREATMENT OF CANCER
The present invention relates to an antibody-drug-conjugate or pharmaceutical composition comprising the same. From one aspect, the invention relates to an antibody-drug-conjugate (ADC) comprising an antibody consisting of the Trastuzumab or a biosimilar thereof, said antibody being conjugated to at least one drug consisting of a monomethyl auristatin F derivative. The invention also comprises method of treatment of cancer comprising administering to the subject an effective amount of said antibody-drug-conjugate or composition comprising the same.
-
Paragraph 0293; 0294

(2017/05/15)

COMPOSITION FOR THE TREATMENT OF IGF-1R EXPRESSING CANCER
The present invention relates to a method for the treatment of IGF-IR expressing cancers as well as to a compositions and a kit for said traitment. From one aspect, the invention reates to the combined use of a first antibody for the determination of the IGF-IR status of a cancer and a second antibody used as an ADC for the treatment of said cancer.
-
Page/Page column 117

(2017/05/17)

Total synthesis and biological activity of dolastatin 16
The total synthesis of dolastatin 16, a macrocyclic depsipeptide first isolated from the sea hare Dolabella auricularia as a potential antineoplastic metabolite by Pettit et al., was achieved in a convergent manner. Dolastatin 16 was reported by Tan to ex
Casalme, Loida O.,Yamauchi, Arisa,Sato, Akinori,Petitbois, Julie G.,Nogata, Yasuyuki,Yoshimura, Erina,Okino, Tatsufumi,Umezawa, Taiki,Matsuda, Fuyuhiko
supporting information
p. 1140 - 1150
(2017/02/10)

Solution-phase synthesis and biological evaluation of triostin A and its analogues
Triostin A is a biosynthetic precursor of echinomycin which is one of the most potent hypoxia inducible factor 1 (HIF-1) inhibitors. An improved solution-phase synthesis of triostin A on a preparative scale has been achieved in 17.5% total yield in 13 ste
Hattori, Kozo,Koike, Kota,Okuda, Kensuke,Hirayama, Tasuku,Ebihara, Masahiro,Takenaka, Mei,Nagasawa, Hideko
supporting information
p. 2090 - 2111
(2016/02/18)

SPECIFIC CONJUGATION LINKERS, SPECIFIC IMMUNOCONJUGATES THEREOF, METHODS OF MAKING AND USES SUCH CONJUGATES THEREOF
The present invention relates to novel linkers containing a 2,3-disubstituted succinic group, or 2-monosubstituted, or 2,3-disubstituted fumaric or maleic (trans (E)- or cis (Z)- butenedioic), or acetylenedicarboxyl group for conjugation of a cytotoxic agent, and/or one or more different functional molecules per linker to a cell-binding molecule, through bridge linking pairs of thiols on the cell-binding molecule specifically. The invention also relates to methods of making such linkers, and of using such linkers in making homogeneous conjugates, as well as of application of the conjugates in treatment of cancers, infections and autoimmune disorders.
-
Page/Page column 121

(2016/05/24)

Design, synthesis, and in vitro antiplasmodial activity of 4-aminoquinolines containing modified amino acid conjugates
Abstract: A new series of side chain-modified 4-aminoquinolines were synthesized and screened for in vitro antiplasmodial activity against both chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. Among the series, compounds 30 and 31 showed significant inhibition of parasite growth against K1 strain of P. falciparum with IC50 values 0.28 and 0.31?μM, respectively, whereas compounds 34, 35, and 38 exhibited superior activity against K1 strain with IC50 values 0.18, 0.22, and 0.17?μM, respectively, as compared to 0.255?μM for chloroquine (CQ). All the compounds displayed good resistance factor between 1.54 and >34.48 as against 51.0 for CQ. All these analogues were found to form strong complex with hematin and inhibited the β-hematin formation in vitro, suggesting that this class of compounds act on a heme polymerization target. Overall results suggest that present series of compounds appear to be promising for further lead optimization to obtain compounds active against drug-resistant parasites. Graphical Abstract: [Figure not available: see fulltext.]
Srinivasarao, Kondaparla,Agarwal, Pooja,Srivastava, Kumkum,Haq,Puri, Sunil K.,Katti
p. 1148 - 1162
(2016/07/06)

CONJUGATE OF MONOMETHYL AURISTATIN F AND TRASTUZUMAB AND ITS USE FOR THE TREATMENT OF CANCER
The present invention relates to an antibody-drug-conjugate. From one aspect, the invention relates to an antibody-drug-conjugate comprising an antibody consisting of the Trastuzumab, said antibody being conjugated to at least one drug consisting of a monomethyl auristatin F derivative. The invention also comprises method of treatment and the use of said antibody-drug-conjugate for the treatment of cancer.
-
Page/Page column 45

(2016/11/17)

Total Synthesis and Biological Evaluation of Tubulysin Analogues
We report a second-generation synthesis of the exceedingly potent antimitotic agent N14-desacetoxytubulysin H (1) as well as the preparation of nine analogues of this lead structure. Highlights of our synthetic efforts include an efficient late
Colombo, Raffaele,Wang, Zhiyong,Han, Junyan,Balachandran, Raghavan,Daghestani, Hikmat N.,Camarco, Daniel P.,Vogt, Andreas,Day, Billy W.,Mendel, David,Wipf, Peter
p. 10302 - 10320
(2016/11/17)

Stereoselective synthesis of hantupeptins A, B and C common fragment
The stereoselective synthesis of the common fragment of Hantupeptine A, B and C is described using N-methylation of aminoacids, HATU mediated coupling reaction and diazotization of L-phenylalanine.
Srinivas,Sunitha,Rao, C. Govind
p. 1239 - 1242
(2017/04/28)

AURISTATIN ANALOGUES AND THEIR CONJUGATES WITH CELL-BINDING MOLECULES
This invention relates to analogues of auristatins, in particular monomethyl auristatin F (MMAF), as cytotoxic agents, conjugates of such cytotoxic agents with a cell-binding agent, the preparation and the therapeutic uses of these cytotoxic agents and conjugates thereof to arrest or retard abnormal cell growth and /or proliferation.
-
Page/Page column 67; 68

(2015/11/18)

NOVEL LINKERS AND THEIR USES IN SPECIFIC CONJUGATION OF DRUGS TO A BIOLOGICAL MOLECULE
The present invention relates to novel linkers containing a 2,3-disubstituted succinic group, or 2-monosubstituted, or 2,3-disubstituted fumaric or maleic (trans (E)- or cis (Z)- butenedioic) group for conjugation of two or more compounds/cytotoxic agents per linker to a cell-binding molecule, through bridge linking pairs of thiols on the cell-binding molecule specifically. The invention also relates to methods of making such linkers, and of using such linkers in making homogeneous conjugates, as well as of application of the conjugates in treatment of cancers, infections and autoimmune disorders.
-
Page/Page column 99

(2015/11/17)

IGF-1R ANTIBODY-DRUG-CONJUGATE AND ITS USE FOR THE TREATMENT OF CANCER
The present invention relates to an antibody-drug-conjugate capable of binding IGF-1R. From one aspect, the invention relates to an antibody-drug-conjugate comprising an antibody capable of binding to IGF-1R, said antibody being conjugated to at least one drug selected from derivatives of dolastatin 10 and auristatins. The invention also comprises method of treatment and the use of said antibody-drug- conjugate for the treatment of cancer.
-
Page/Page column 115

(2015/11/16)

ANTIBODY-DRUG-CONJUGATE AND ITS USE FOR THE TREATMENT OF CANCER
The present invention relates to an antibody-drug-conjugate. From one aspect, the invention relates to an antibody-drug-conjugate comprising an antibody capable of binding to a Target, said antibody being conjugated to at least one drug selected from derivatives of dolastatin 10 and auristatins. The invention also comprises method of treatment and the use of said antibody-drug-conjugate for the treatment of cancer.
-
Page/Page column 135; 136

(2015/11/10)

Asymmetric reduction of imines with trichlorosilane catalyzed by valine-derived formamide immobilized onto magnetic nano-Fe3O4
Magnetic nano-Fe3O4-supported organocatalysts were synthesized by anchoring valine-derived formamide onto the surface of Fe3O4 magnetic nanoparticles, which were applied in the asymmetric reduction of imines wit
Ge, Xin,Qian, Chao,Ye, Xiaoming,Chen, Xinzhi
p. 65402 - 65407
(2015/08/18)

Synthesis of novel carbohydrate-based valine-derived formamide organocatalysts by CuAAC click chemistry and their application in asymmetric reduction of imines with trichlorosilane
Novel organocatalysts combining carbohydrate and N-formyl-l-valine derivatives were prepared by CuII-catalyzed diazo transfer and CuI-catalyzed azide-alkyne 1,3-dipolar cycloaddition CuAAC click chemistry. It was found that the carbohydrate-based valine-derived formamide organocatalyst had high catalytic activity for the asymmetric reduction of imines with trichlorosilane. The reduction can proceed at room temperature in toluene in high yield (up to 98%) and with excellent enantioselectivity (up to 94%). 'CuAAC' click chemistry is a bridge to link N-formyl-l-valine derived organocatalysts with carbohydrates.
Ge, Xin,Qian, Chao,Chen, Xinzhi
p. 1450 - 1455
(2015/01/08)

DERIVATIVES OF DOLASTATIN 10 AND AURISTATINS
The present invention concerns a compound of following formula (I): where: - R1 is H or OH, - R2 is a (C1-C6)alkyl, COOH, COO-((C1-C6)alkyl) or thiazolyl group, - R3 is H or a (C1-C6)alkyl group, and - R4 is: ■ a straight-chain or branched, saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms substituted by one or more groups chosen from among OH and NR5R6, ■ -(CH2CH2X1)(CH2CH2X2)a2(CH2CH2X3)a3(CH2CH2X4)a4(CH2CH2X5)a5R7, ■ an aryl-(C1-C8)alkyl group substituted by one or more groups chosen from among OH and NR9R10 groups, or ■ a heterocycle-(C1-C8)alkyl group optionally substituted by one or more groups chosen from among (C1-C6)alkyl, OH and NR12R13 groups, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and its uses in particular for the treatment of cancer, pharmaceutical compositions containing the same and the preparation methods thereof.
-
Page/Page column 38

(2014/11/13)

DERIVATIVES OF DOLASTATIN 10 AND AURISTATINS
The present invention concerns a compound of following formula (I) where: - R1 is H or OH, - R2 is a (C1-C6)alkyl, COOH, COO-((C1-C6)alkyl) or thiazolyl group, - R3 is H or a (C1-C6)alkyl group, and - R4 is an aryl-(C1-C8)alkyl group substituted by one or more groups chosen from among OH and NR9R10 groups, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and its uses in particular for the treatment of cancer, pharmaceutical compositions containing the same and the preparation methods thereof.
-
Page/Page column 31

(2014/11/13)

DERIVATIVES OF DOLASTATIN 10 AND AURISTATINS
The present invention concerns a compound of following formula (I) where: - R1 is H or OH, - R2 is a (C1-C6)alkyl, COOH, COO-((C1-C6)alkyl) or thiazolyl group, - R3 is H or a (C1-C6)alkyl group, and - R4 is: - an aryl-(C1-C8)alkyl group substituted by one or more groups chosen from among OH and NR9R10 groups, or - a heterocycle-(C1-C8)alkyl group optionally substituted by one or more groups chosen from among (C1-C6)alkyl, OH and NR12R13 groups, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and its uses in particular for the treatment of cancer, pharmaceutical compositions containing the same and the preparation methods thereof.
-
Page/Page column 34; 35

(2014/11/13)

Total synthesis of the Marine cyclic depsipeptide viequeamide A
The first total synthesis of viequeamide A, a natural cyclic depsipeptide isolated from a marine button cyanobacterium, was achieved with the N-Me-Val-Thr peptide bond as the final macrocyclization site. The synthetic product gave nearly identical spectroscopic data to that reported for the natural product.
Wang, Dongyu,Song, Shanshan,Tian, Ye,Xu, Youjun,Miao, Zehong,Zhang, Ao
supporting information
p. 974 - 978
(2013/07/05)

Design, SAR, angiogenic activities evaluation and pro-angiogenic mechanism of new marine cyclopeptide analogs
Angiogenesis plays an important role in a wide range of physiological processes. In this paper, we designed and synthesized a series of new analogs including 11 line-peptides and 9 cyclo-peptides by using a marine cyclopeptide (compound 21) which could st
Li,Lu,Wu,Yu,Xu,Qiu,Pei,Lin,Pang
p. 1183 - 1194
(2013/07/28)

The multicomponent approach to N-methyl peptides: Total synthesis of antibacterial (-)-viridic acid and analogues
Two syntheses of natural viridic acid, an unusual triply N-methylated peptide with two anthranilate units, are presented. The first one is based on peptide-coupling strategies and affords the optically active natural product in 20% overall yield over six steps. A more economical approach with only four steps leads to the similarly active racemate by utilizing a Ugi four-component reaction (Ugi-4CR) as the key transformation. A small library of viridic acid analogues is readily available to provide first SAR insight. The biological activities of the natural product and its derivatives against the Gram-negative bacterium Aliivibrio fischeri were evaluated.
Neves Filho, Ricardo A. W.,Stark, Sebastian,Westermann, Bernhard,Wessjohann, Ludger A.
supporting information
p. 2085 - 2090
(2013/02/22)

Total synthesis of the proposed structure of cyclic hexadepsipeptide veraguamide A
We have developed a practical method to assemble the proposed structure of natural product veraguamide A (1) by first preparing the three key fragments followed by optimization of the macrocyclization site. Although the synthetic product gave similar optical rotation to that reported for natural product, significant differences in the 1H and 13C NMR spectra were observed, especially the proton and carbon signals in the two N-MeVal moieties.
Wang, Dongyu,Jia, Xian,Zhang, Ao
supporting information; experimental part
p. 7027 - 7030
(2012/09/22)

Total synthesis, absolute configuration, and biological activity of xyloallenoide A
The novel natural product xyloallenoide A, isolated from the marine mangrove endophytic fungus from the South China Sea, and its diastereoisomer xyloallenoide A1, which contain N-methyl-substituted amino acids, were synthesized. The absolute configurations of the amino acid units of xyloallenoide A were finally confirmed to be L-Lys, Me-D-Val, and Me-L-Ala. This report represents a practical and attractive alternative for the synthesis of N-methyl-substituted cyclotripeptides. In the preliminary bioassay, synthetic xyloallenoide A showed marginal activities against KB (IC50=9.6 mm) and KBv200 cells (IC50=10.3 μm), and xyloallenoide A1 was inactive against KB and KBv200 cells.
Wang, San-Yong,Xu, Zhong-Liang,Wang, Hui,Li, Chun-Rong,Fu, Li-Wu,Pang, Ji-Yan,Li, Jing,She, Zhi-Gang,Lin, Yong-Cheng
experimental part
p. 973 - 982
(2012/08/08)

A total synthesis of the ammonium ionophore, (-)-enniatin B
A nine-step (longest linear) batch total synthesis of the cyclic hexadepsipeptide (-)-enniatin B is described. The synthesis minimizes precipitation during reaction conditions for adaptability to flow synthesis. The route was used to prepare >100 mg of th
Hu, Dennis X.,Bielitza, Max,Koos, Peter,Ley, Steven V.
supporting information; experimental part
p. 4077 - 4079
(2012/09/07)

Marine cyclotripeptide X-13 promotes angiogenesis in zebrafish and human endothelial cells via PI3K/Akt/eNOS signaling pathways
Cyclotripeptide X-13 is a core of novel marine compound xyloallenoide A isolated from mangrove fungus Xylaria sp. (no. 2508). We found that X-13 dose-dependently induced angiogenesis in zebrafish embryos and in human endothelial cells, which was accompanied by increased phosphorylation of eNOS and Akt and NO release. Inhibition of PI3K/Akt/eNOS by LY294002 or L-NAME suppressed X-13-induced angiogenesis. The present work demonstrates that X-13 promotes angiogenesis via PI3K/Akt/eNOS pathways.
Lu, Xi-Lin,Xu, Zhong-Liang,Yao, Xiao-Li,Su, Feng-Juan,Ye, Cheng-Hui,Li, Jing,Lin, Yong-Cheng,Wang, Guang-Lei,Zeng, Jin-Sheng,Huang, Ru-Xun,Ou, Jing-Song,Sun, Hong-Shuo,Wang, Li-Ping,Pang, Ji-Yan,Pei, Zhong
scheme or table
p. 1307 - 1320
(2012/08/08)

Overturning indolyne regioselectivities and synthesis of indolactam V
We report the design and synthesis of an indolyne that displays a reversal in regioselectivity, in both nucleophilic addition and cycloaddition reactions, compared to typical 4,5-indolynes. Our approach utilizes simple computations to predict regioselectivity in reactions of unsymmetrical arynes. With this methodology, novel benzenoid-substituted indoles can be accessed with significant regiocontrol. Furthermore, the technology provides an unconventional tactic for the synthesis of C4-substituted indole alkaloids, as demonstrated by a synthesis of indolactam V.
Bronner, Sarah M.,Goetz, Adam E.,Garg, Neil K.
supporting information; experimental part
p. 3832 - 3835
(2011/04/27)

On the selective N-methylation of BOC-protected amino acids
(Chemical Equation Presented) The selective N-methylation of BOC-protected valine 1a with MeI and NaH in THF (i.e., in the presence of a free carboxyl group) has been attributed to the protection of the carboxylate by chelation to Na+. An alternative mechanism, involving the formation of the carbene intermediate generated from MeI and its insertion into the N-H bond, has been ruled out by isotopic labeling. 2009 American Chemical Society.
Malkov, Andrei V.,Vrankova, Kvetoslava,Cerny, Miloslav,Kocovsky, Pavel
experimental part
p. 8425 - 8427
(2010/01/16)

Asymmetric transfer hydrogenation of ketimines with trichlorosilane: Structural studies
We report structural and mechanistic studies on the organocatalytic asymmetric transfer hydrogenation of ketimines with trichlorosilane. Amines were obtained in good yields and moderate enantioselectivities. Both experiment and computation were utilized to provide an improved understanding of the mechanism. Georg Thieme Verlag Stuttgart.
Zhang, Zhiguo,Rooshenas, Parham,Hausmann, Heike,Schreiner, Peter R.
experimental part
p. 1531 - 1544
(2009/12/09)

New organocatalysts for the asymmetric reduction of imines with trichlorosilane
Asymmetric reduction of prochiral ketimines 1a-f with trichlorosilane can be catalyzed by the Lewis-basic formamides (S)-4a,b, derived from N-methyl valine, with ≤91% enantioselectivity and low catalyst loading (≤5 mol %) at room temperature in toluene.
Malkov, Andrei V.,Vranková, Kvetoslava,Sigerson, Ralph C.,Ston?ius, Sigitas,Ko?ovsky, Pavel
experimental part
p. 9481 - 9486
(2009/12/26)

Organocatalysis with a fluorous tag: Asymmetric reduction of imines with trichlorosilane catalyzed by amino acid-derived formamides
(Chemical Equation Presented) Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by N-methylvaline-derived Lewis-basic formamides 3a-d with high enantioselectivity (≤95% ee) and low catalyst loading (1-5 mol %) at room temperature i
Malkov, Andrei V.,Figlus, Marek,Stoncius, Sigitas,Kocovsky, Pavel
p. 1315 - 1325
(2007/10/03)

Enantioselective synthesis of 1,2-diarylaziridines by the organocatalytic reductive amination of α-chloroketones
(Chemical Equation Presented) One-sided triangles: A simple protocol has been developed for the synthesis of highly useful single enantiomers of 1,2-diarylaziridines. The method involves conversion of the readily available α-chloroacetophenones into the c
Malkov, Andrei V.,Stoncius, Sigitas,Kocovsky, Pavel
p. 3722 - 3724
(2008/02/13)

Formamides derived from N-methyl amino acids serve as new chiral organocatalysts in the enantioselective reduction of aromatic ketimines with trichlorosilane
Asymmetric reduction of N-aryl ketimines 1a-k, 43, and 45 with trichlorosilane can be catalyzed by new N-methyl l-amino acid-derived Lewis-basic organocatalysts, such as the valine-derived bisamide 3d (10 mol%), in toluene at room temperature with high enantioselectivity (≤92% ee). The structure-reactivity investigation shows that the product configuration is controlled by the nature of the side chain of the catalyst scaffold (e.g., i-Pr vs Me, as in 3d and 6e), so that catalysts of the same absolute configuration may induce the formation of the opposite enantiomers of the product. Arene-arene interactions between the catalyst and the incoming imine appear to be the prerequisite for asymmetric induction. This metal-free, organocatalytic protocol is competitive with the traditional, metal-catalyzed methodology.
Malkov, Andrei V.,Ston?ius, Sigitas,MacDougall, Kenneth N.,Mariani, Andrea,McGeoch, Grant D.,Ko?ovsky, Pavel
p. 264 - 284
(2007/10/03)

Asymmetric total syntheses of marine cyclic depsipeptide halipeptins A-D
Halipeptins A-D (1a-d) are a family of natural cyclic depsipeptides isolated from marine sponges. Total syntheses of these four compounds are detailed in this report. The key elements in this synthesis include the elaboration of the polysubstituted decanoic acid parts by two asymmetric aldol reactions, assembly of the N-methyl-δ-hydroxyisoleucine residue by using either aza-Claisen rearrangement or methylation of aspartates as the key steps, and macrocyclization at the polysubstituted decanoic acid alanine site.
Yu, Shouyun,Pan, Xianhua,Ma, Dawei
p. 6572 - 6584
(2008/09/16)

Chemical mediators: The remarkable structure and host-selectivity of depsilairdin, a sesquiterpenic depsipeptide containing a new amino acid
(Chemical equation presented) The chemical structure determination of depsilairdin, a highly selective phytotoxin produced by the plant pathogenic fungus Leptosphaeria maculans/Phoma lingam, is described. The elucidation of the unusual chemical structure
Pedras, M. Soledade C.,Chumala, Paulos B.,Wilson Quail
p. 4615 - 4617
(2007/10/03)

Role of noncovalent interactions in the enantioselective reduction of aromatic ketimines with trichlorosilane
Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by a new N-methyl L-valine derived Lewis basic organocatalyst, such as 4d, with high enantioselectivity. The structure-reactivity investigation suggests hydrogen bonding and arene-arene interactions between the catalyst and the incoming imine as the main factor determining the enantiofacial selectivity.
Malkov, Andrei V.,Mariani, Andrea,MacDougall, Kenneth N.,Kocovsky, Pavel
p. 2253 - 2256
(2007/10/03)

An efficient and practical N-methylation of amino acid derivatives.
[reaction: see text] An efficient and practical N-methylation of amino acid derivatives with dimethyl sulfate in the presence of sodium hydride and a catalytic amount of water is described. Reaction of water with sodium hydride generated highly reactive dry sodium hydroxide, which led to much faster reaction rates than powdered sodium hydroxide itself.
Prashad, Mahavir,Har, Denis,Hu, Bin,Kim, Hong-Yong,Repic, Oljan,Blacklock, Thomas J
p. 125 - 128
(2007/10/03)

New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica: 2. Structure analysis
The structures of new cyclic decadepsipeptides, clavariopsins A and B, were determined to be cyclo[-(R)-2-hydroxyisovaleryl-L-pipecolyl-L-MeVal- L-Val-L-MeAsp-L-Melle-L-Melle-Gly-L-MeVal-L-Tyr(OMe)-] and cyclo[-(R)-2- hydroxyisovaleryl-L-pipecoly-L-Val-L-Val-L-MeAsp-L-Melle-L-Melle-Gly-L- MeVal-L-Tyr(OMe)-], respectively, by spectroscopic analyses, especially using 2D NMR techniques. The absolute stereochemistry was elucidated by the advanced Marfey's method and chiral HPLC analysis.
Suzuki,Ojika,Sakagai,Kaida,Fudou,Kameyama
p. 22 - 28
(2007/10/03)

1-Ethyl 2-halopyridinium salts, highly efficient coupling reagents for hindered peptide synthesis both in solution and the solid-phase
1-Ethyl-2-halopyridinium salts, BEP, FEP, BEPH and FEPH, were synthesized and proved to be very effective for the synthesis of hindered peptides containing N-methylated or C(α),C(α)-dialkylated amino acid residues. HPLC monitoring of model reactions indicated that these pyridinium salts demonstrated higher reactivities, lower racemization than the commonly used halogenated uronium and phosphonium salts. The efficiency of these pyridinium type coupling reagents was further proved by the synthesis of a series of hindered oligopeptides and active esters with good yields and convenient workup. The 8-11 tetrapeptide fragment of Cyclosporin A (CsA) and the pentapeptide moiety of Dolastatin 15 were also successfully synthesized using these pyridinium salts. The efficiency of these pyridinium type coupling reagents for SPPS was also demonstrated by the solid-phase synthesis of the extremely hindered 8-11 peptide segment of CsA and the linear undecapeptide of CsO. The mechanism of the pyridinium salt mediated coupling reactions was also studied by 1H NMR, IR and HPLC. It was proposed that the major reactive intermediates were the corresponding acyl halide and acyloxypyridinium salts of the N-protected amino acid or peptide. (C) 2000 Elsevier Science Ltd.
Li, Peng,Xu, Jie-Cheng
p. 8119 - 8131
(2007/10/03)

A simple and rapid protocol for N-methyl-α-amino acids
A two step strategy for optically pure N-Protected-N-methyl-α-amino acids starting from N-protected-α-amino acids via reductive cleavage of oxazolidinones using NaCNBH3/TMSCl is described.
Reddy, G. Vidyasagar,Iyengar
p. 299 - 300
(2007/10/03)

Anti-fungal agents
Compounds of the formula STR1 or pharmaceutically acceptable salts thereof wherein R1, R2, X1, X2, X3, X4, X5, X6, X7, and X8, are as set forth herein are described. These compounds are useful as agents in the treatment of fungal infections.
-
(2008/06/13)

A practical approach for the optically pure N-Methyl-α- amino acids
A new practical synthesis of N-Methyl-α-amino acids by racemization free methodology has been developed. The method involves the reductive cleavage of N-protected oxazotidinones using hydrogen in the presence of Pd/C to give the title compounds in quantitative yields.
Reddy, G. Vidyasagar,Rao, G. Venkat,Iyengar
p. 1985 - 1986
(2007/10/03)

Rational design and synthesis of unsaturated 2,5-dioxopiperazine derivatives as potential protein tyrosine kinase inhibitors
The first general method for the synthesis of a library of trifunctionalized (Z)-3-alkylidene-2,5-piperazinediones as potential protein tyrosine kinase inhibitors from commercially available amino compounds, α- keto acids and aldehydes using a novel cyclization/cleavage strategy on solid support is described.
Li, Wen-Ren,Peng, Shao-Zheng
p. 7373 - 7376
(2007/10/03)