- Electrochemical Dimethyl Sulfide-Mediated Esterification of Amino Acids
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Dimethyl sulfide-mediated electrochemical synthetic strategy for esterification of amino acids has been reported. A series of amino acids could react smoothly with alcohols, affording the desired esterification products with good efficiency. Importantly, the tolerance of peptides and gram-scale synthesis shed light on the utility of this protocol. Mechanistically, the dimethyl sulfide as a mediator plays an essential role in the transformation of amino acids.
- Li, Yongli,Wang, Huamin,Zhang, Heng,Lei, Aiwen
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supporting information
p. 3023 - 3028
(2021/08/30)
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- Simple and Practical Real-Time Analysis of Solid-Phase Reactions by Thin-Layer Chromatography
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Solid-phase synthesis is a practical approach for simplifying the time-consuming and routine purification steps in the preparation of numerous naturally occurring molecules; however, studying such reactions is difficult due to the lack of a convenient monitoring method. By using thin-layer chromatography in conjunction with a photolabile linker on a resin, we developed a convenient and simple method for monitoring solid-phase reactions in real time by thin-layer chromatography. This method provides a user-friendly protocol for examining reaction conditions for solid-state syntheses.
- Wu, Chia-Hui,Chen, Chun C.,Lin, Su-Ching,Wang, Cheng-Chung
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supporting information
p. 1430 - 1436
(2018/05/15)
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- Synthesis method of Fmoc-O-tert-butyl-L-threoninol
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The present invention relates to a synthesis method of Fmoc-O-tert-butyl-L-threoninol, and mainly solves the technical problems that in a process of Fmoc-thr(tbu)-oh reduction by sodium borohydride, the reaction temperature is strictly required and a FMoc protecting group is decomposed, resulting in low yield and high cost. The synthesis method of the invention comprises the following steps: a. L-threonine reacts with thionyl chloride to form L-threonine methyl ester hydrochloride; b. the L-threonine methyl ester hydrochloride under the action of sodium hydroxide is reacted with benzyl chloroformate to produce z-thr-ome; c. the Z-thr-ome reacts with introduced isobutene in the presence of methylene chloride and concentrated sulfuric acid, and alkali adjustment treatment is carried out to obtain z-thr (tbu)-ome; d. in the presence of acetone and water, the Z-thr(tbu)-ome is saponified with added alkali to obtain z-thr(tbu)-oh; e. the Z-thr(tbu)-oh is reduced to z-thr(tbu)-ol by sodium borohydride in tetrahydrofuran; f. the z-thr(tbu)-ol is hydrogenated in methanol to obtain H-thr(tbu)-ol; and g. N-(9-fluorenylmethoxycarbonyloxy)succinimide is added to the H-thr(tbu)-ol to obtain the Fmoc-O-tert-butyl -L-threoninol.
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Paragraph 0015
(2017/07/12)
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- Ammonia curved the monocyclic parent nucleus method for the preparation of
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The invention relates to a preparation of Aztreonam monocyclic parent nucleus method, in the method using benzyl chloroformate under strongly acidic conditions the protection, the sodium carbonate is used to carry out closed-loop reaction, the reaction is stable, is greatly improved yield, total yield of 48% the advantages.
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Paragraph 0030; 0031
(2017/01/26)
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- SPIRO-LACTAM NMDA RECEPTOR MODULATORS AND USES THEREOF
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Disclosed are compounds having enhanced potency in the modulation of NMDA receptor activity. Such compounds are contemplated for use in the treatment of conditions such as depression and related disorders. Orally available formulations and other pharmaceutically acceptable delivery forms of the compounds, including intravenous formulations, are also disclosed.
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Paragraph 00283; page 177
(2014/08/19)
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- SPIRO-LACTAM NMDA RECEPTOR MODULATORS AND USES THEREOF
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Disclosed are compounds having enhanced potency in the modulation of NMDA receptor activity. Such compounds are contemplated for use in the treatment of conditions such as depression and related disorders. Orally available formulations and other pharmaceutically acceptable delivery forms of the compounds, including intravenous formulations, are also disclosed.
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Paragraph 0107
(2014/08/19)
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- Highly efficient and selective phosphorylation of amino acid derivatives and polyols catalysed by 2-aryl-4-(dimethylamino)pyridine-N-oxides-towards kinase-like reactivity
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The chemoselective phosphorylation of hydroxyl containing amino acid derivatives and polyols by phosphoryl chlorides catalyzed by 2-aryl-4-(dimethylamino)pyridine-N-oxides is described.
- Murray, James I.,Woscholski, Rudiger,Spivey, Alan C.
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supporting information
p. 13608 - 13611
(2015/01/09)
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- Total synthesis of the Bacteroides fragilis zwitterionic polysaccharide a1 repeating unit
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Nearly all bacteria capsular polysaccharides are T-cell-independent antigens that do not promote immunoglobulin class switching from IgM to IgG nor memory responses. In contrast, zwitterionic polysaccharides activate T-cell-dependent immune responses by m
- Pragani, Rajan,Seeberger, Peter H.
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supporting information; scheme or table
p. 102 - 107
(2011/03/17)
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- Mild and catalytic transesterification reaction using K2HPO 4 for the synthesis of methyl esters
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K2HPO4 is an efficient catalyst for the transesterification reaction to produce methyl esters. Various functional groups are compatible under the mild reaction conditions. Georg Thieme Verlag Stuttgart New York.
- Shinada, Tetsuro,Hamada, Makoto,Miyoshi, Kota,Higashino, Masato,Umezawa, Taiki,Ohfune, Yasufumi
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experimental part
p. 2141 - 2145
(2010/11/02)
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- De novo synthesis of a 2-acetamido-4amino-2,4,6-trideoxy-d-galactose (AAT) building block for the preparation of a bacteroides fragilis a1 polysaccharide fragment
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(Figure Presented) Zwitterionic polysaccharides (ZPSs) are potent T-cell activators that naturally occur on the cell surface of bacteria and show potential as immunostimulatory agents. An unusual, yet important component of many ZPSs is 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT). AAT building block 2 was prepared via a de novo synthesis from N-Cbz-L-threonine 5. Furthermore, building block 2 was used to synthesize disaccharide 15 that constitutes a fragment of zwitterionic polysaccharide A1 (PS A1) found in Bacteroldes fragilis.
- Pragani, Rajan,Stallforth, Pierre,Seeberger, Peter H.
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supporting information; experimental part
p. 1624 - 1627
(2010/06/17)
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- UREA DERIVATIVES AS ANTIBACTERIAL AGENTS
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This invention relates to compounds of the Formula (I):or a pharmaceutically acceptable salt, solvate, ester or isomer thereof, which is useful for the treatment of diseases or conditions mediated by LpxC.
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Page/Page column 44-45
(2010/04/03)
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- Trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted facile deprotection of N,O-acetonides
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(Chemical Equation Presented) Employing TMSOTf as an easily available reagent, we have developed a mild and efficient method for the deprotection of both terminal and internal N,O-acetonide functionalities. Various regularly used protecting groups and com
- Poon, Kevin W. C.,Lovell, Kimberly M.,Dresner, Kendra N.,Datta, Apurba
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p. 752 - 755
(2008/09/18)
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- New boron(III)-catalyzed amide and ester condensation reactions
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In 1996, we reported that benzeneboronic acids bearing electron-withdrawing groups at the meta- or para-position are highly effective catalysts for the amide condensation reaction in less-polar solvents. In this paper, we report that N-alkyl-4-boronopyridinium halides are more effective catalysts than the previous ones in more polar solvents. N-Alkyl-4-boronopyridinium halides are effective not only for amide condensation between equimolar mixtures of carboxylic acids and amines but also for the esterification of α-hydroxycarboxylic acids in alcohol solvents. Furthermore, perchlorocatecholborane is more effective than areneboronic acids for the amide condensation of sterically demanding carboxylic acids. In addition, Lewis acid-assisted Br?nsted acid (LBA), which is prepared from a 1:2 M mixture of boric acid and tetrachlorocatechol, is effective for the Ritter reaction from alcohols and nitriles to amides.
- Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 8645 - 8657
(2008/02/08)
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- N-alkyl-4-boronopyridinium halides versus boric acid as catalysts for the esterification of α-hydroxycarboxylic acids
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(Chemical Equation Presented) Boric acid is a highly effective catalyst for the dehydrative esterification reaction between equimolar mixtures of α-hydroxycarboxylic acids and alcohols. In contrast, N-methyl-4- boronopyridinium iodide (2a) is a more effective catalyst than boric acid for the similar esterification in excess alcohol. A heterogeneous catalyst, such as N-polystyrene-bound 4-boronopyridinium chloride, is also an effective catalyst and can be recovered by filtration.
- Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 5047 - 5050
(2007/10/03)
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- Total synthesis and revision of stereochemistry of the marine metabolite trunkamide A
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The isolation of the cytotoxic Lissoclinum sp. metabolite trunkamide A was reported in 1996. After completion of a total synthesis in 1999, it became clear that the structure of this marine natural product had to be revised. We now report the first preparation of actual trunkamide A in a total synthesis that serves as an unambiguous structural and stereochemical proof. Highlights of our synthetic strategy are a Lewis acid assisted aziridine opening that was used for the preparation of the novel reverse- prenylated serine and threonine side chains as well as an efficient oxazoline-thiazoline interconversion on the macrocyclic skeleton. In addition, several stereoisomers prepared by complementary synthetic protocols serve to illustrate the general scope of our methodology and confirm the configurational assignment.
- Wipf, Peter,Uto, Yoshikazu
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p. 1037 - 1049
(2007/10/03)
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- Synthesis of acyclic nucleoside and nucleotide analogues from amino acids: A convenient approach to a PMEA-PMPA hybrid
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Nonracemic amino alcohols derived from common amino acids have been used to assemble acyclic nucleoside and nucleotide analogues with control of absolute stereochemistry. Both (R)- and (S)-2-amino-1-propanol, readily available from D- or L-alanine, were used to prepare the nucleoside analogues (R)- and (S)-9-[1- methyl-2-hydroxyethyl]adenine, and then the nucleotide analogues (R)- and (S)-9-[1-methyl-2-phosphonomethoxyethyl]adenine. In a similar fashion, the CBz derivative of L-threonine was used to prepare first (1R,2R)-9-[1-hydroxymethyl-2-hydroxypropyl]adenine, and then the bis phosphonomethoxy derivative. The bis phosphonate derived from threonine represents a unique structural hybrid of PMEA and PMPA, both of which have well established antiviral activity. (C) 2000 Elsevier Science Ltd.
- Jeffery, Arlen L.,Kim, Jae-Hun,Wiemer, David F.
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p. 5077 - 5083
(2007/10/03)
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- High yielding synthesis of dehydroamino acid and dehydropeptide derivatives
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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
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p. 3697 - 3703
(2007/10/03)
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- Oxazaborolidine-mediated asymmetric reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones
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Highly enantioselective reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones was conducted using oxazaborolidine derived from L-threonine and borane complexes to give β- imino alcohols and 1,2-diaryl-1,2-ethanediols in high enantiomeric purity. Subsequent reduction of the imino functionality of the former products afforded either syn- or anti-2-amino-1,2-diarylethanols in high enantiomeric purity by choosing appropriate reduction methods.
- Shimizu, Makoto,Tsukamoto, Keiko,Matsutani, Takayuki,Fujisawa, Tamotsu
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p. 10265 - 10274
(2007/10/03)
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- Stereocontrol in the reduction of 1,2-diimine with an oxazaborolidine catalyst. Highly stereoselective preparation of (R,R)-1,2-diphenylethylenediamine
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Highly enantioselective reduction of 1,2-bis(p-methoxyphenylimino)-1,2-diphenylethane was conducted even with 0.5 mol% of new oxazaborolidine derived from L-threonine and a stoichiometric amount of BH3·THF to give 1,2-diphenylethylenediamine derivative in excellent enantiomeric purity. The subsequent deprotection of nitrogen atoms afforded (R,R)-1,2-diphenylethylenediamine in enantiomerically pure form.
- Shimizu, Makoto,Kamei, Mie,Fujisawa, Tamotsu
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p. 8607 - 8610
(2007/10/02)
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- π-Facial selection in intermolecular Diels-Alder reactions: Total syntheses of (+)-actinobolin and (+)-5,6,10-triepi-actinobolin
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Syntheses of both 5,6,10-triepi-actinobolin and the antibiotic actinobolin are described in which a homochiral diene prepared from L-threonine is employed as a key componenet in a Diels-Alder reaction with an acetylenic dienophile. While the Diels-Alder reaction of this diene with methyl propiolate furnished the cycloadduct required for the synthesis of (+)-actinobolin as the minor diastereomer, the completion of the synthesis required but seven additional steps. The steric and stercoelectronic features responsible for the π-facial course of this cycloaddition reaction are discussed along with the various steps required to complete the syntheses of the title compounds.
- Kozikowski,Nieduzak,Konoike,Springer
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p. 5167 - 5175
(2007/10/02)
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- Routes to Mitomycins. Chirospecific Synthesis of Aziridinomitosenes
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The syntheses of ethyl (1R,2R)-1,2-(N-benzylaziridino)-7-methoxy-6-methyl-2,3,5,8-tetrahydro-5,8-dioxo-1H-pyrroloindole-9-carboxylate (59) and a regioisomeric aziridinoindoloquinone 60 are presented.Aziridine ring closure on a tricyclic indoloquinone nucleus and on monocyclic pyrrolidine derivatives was unsuccessful but did succeed with the acyclic educt.Thus the synthesis of the target aziridinomitosene was achieved by aziridine ring closure on the asymmetric 2-amino-3-hydroxy-4-azidobutanoate 49 followed by homologation and reductive ring closure to the bicyclic aziridinopyrrolidine 54.Subsequent reduction, regiospecific addition to 2,3-dibromo-5-methoxy-6-methylbenzoquinone (27), photochemical rearrangement, oxidation, and palladium-catalyzed ring closure afforded the (R,R)-aziridinomitosene 59.Regioisomeric aziridinoindoloquinone 60 was obtained directly by the addition of bicyclic aziridine 54 to dibromoquinone 27 followed by copper(II)-catalyzed ring closure.
- Shaw, Kenneth J.,Luly, Jay R.,Rapoport, Henry
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p. 4515 - 4523
(2007/10/02)
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