Introduction of 9-fluorenylmethyloxycarbonyl, trichloroethoxycarbonyl, and benzyloxycarbonyl amine protecting groups into O-unprotected hydroxyamino acids using succinimidyl carbonates

1982 ◽  
Vol 60 (8) ◽  
pp. 976-980 ◽  
Author(s):  
Alenka Paquet
Keyword(s):  
Benzyl Ester ◽  
Protecting Groups ◽  
Efficient Conversion ◽  
Hydroxyamino Acids ◽  
High Yields ◽  
Derivatives Of ◽  
Acid Esters ◽  
Efficient Reagent

9-Fluorenylmethyl succinimidyl, pentachlorophenyl, and benzotriazole-1-yl carbonates were prepared and their reactivity with L-serine and L-serine benzyl ester was compared. The most efficient reagent, 9-fluorenylmethyl succinimidyl carbonate, was used for the preparation of 9-fluorenylmethyloxycarbonyl derivatives of other hydroxyamino acids and hydroxyamino acid esters in high yields. The use of trichloroethyl and benzyl succinimidyl carbonates for an efficient conversion of hydroxyamino acids and their esters into the corresponding N-trichloroethoxycarbonyl and benzyloxycarbonyl derivatives is described.

Hafnium(IV) Chloride Catalyzes Highly Efficient Acetalization of Carbonyl Compounds

2019 ◽  
Vol 16 (6) ◽  
pp. 913-920 ◽  
Author(s):  
Israel Bonilla-Landa ◽  
Emizael López-Hernández ◽  
Felipe Barrera-Méndez ◽  
Nadia C. Salas ◽  
José L. Olivares-Romero
Keyword(s):  
Microwave Heating ◽  
Reaction Times ◽  
Protecting Groups ◽  
Catalyst Loading ◽  
Selective Protection ◽  
Highly Efficient ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
Novel Catalyst ◽  
Acid Labile

Background: Hafnium(IV) tetrachloride efficiently catalyzes the protection of a variety of aldehydes and ketones, including benzophenone, acetophenone, and cyclohexanone, to the corresponding dimethyl acetals and 1,3-dioxolanes, under microwave heating. Substrates possessing acid-labile protecting groups (TBDPS and Boc) chemoselectively generated the corresponding acetal/ketal in excellent yields. Aim and Objective: In this study. the selective protection of aldehydes and ketones using a Hafnium(IV) chloride, which is a novel catalyst, under microwave heating was observed. Hence, it is imperative to find suitable conditions to promote the protection reaction in high yields and short reaction times. This study was undertaken not only to find a novel catalyst but also to perform the reaction with substrates bearing acid-labile protecting groups, and study the more challenging ketones as benzophenone. Materials and Methods: Using a microwave synthesis reactor Monowave 400 of Anton Paar, the protection reaction was performed on a raging temperature of 100°C ±1, a pressure of 2.9 bar, and an electric power of 50 W. More than 40 substrates have been screened and protected, not only the aldehydes were protected in high yields but also the more challenging ketones such as benzophenone were protected. All the products were purified by simple flash column chromatography, using silica gel and hexanes/ethyl acetate (90:10) as eluents. Finally, the protected substrates were characterized by NMR 1H, 13C and APCI-HRMS-QTOF. Results: Preliminary screening allowed us to find that 5 mol % of the catalyst is enough to furnish the protected aldehyde or ketone in up to 99% yield. Also it was found that substrates with a variety of substitutions on the aromatic ring (aldehyde or ketone), that include electron-withdrawing and electrondonating group, can be protected using this methodology in high yields. The more challenging cyclic ketones were also protected in up to 86% yield. It was found that trimethyl orthoformate is a very good additive to obtain the protected acetophenone. Finally, the protection of aldehydes with sensitive functional groups was performed. Indeed, it was found that substrates bearing acid labile groups such as Boc and TBDPS, chemoselectively generated the corresponding acetal/ketal compound while keeping the protective groups intact in up to 73% yield. Conclusion: Hafnium(IV) chloride as a catalyst provides a simple, highly efficient, and general chemoselective methodology for the protection of a variety of structurally diverse aldehydes and ketones. The major advantages offered by this method are: high yields, low catalyst loading, air-stability, and non-toxicity.

ChemInform Abstract: Anionic Derivatives of Pentafluoro-λ6-sulfanyl (Fluorosulfonyl) Acetic Acid Esters.

ChemInform ◽  
2010 ◽  
Vol 25 (7) ◽  
pp. no-no
Author(s):  
R. WINTER ◽  
G. L. GARD ◽  
R. MEWS ◽  
M. NOLTEMEYER
Keyword(s):  
Acetic Acid ◽  
Derivatives Of ◽  
Acetic Acid Esters ◽  
Acid Esters

Bis(ether) derivatives of tetrakis(2-hydroxyphenyl)ethene — Direct synthesis of (E)- and (Z)-bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene via the McMurry olefination reaction

2006 ◽  
Vol 84 (10) ◽  
pp. 1250-1253 ◽  
Author(s):  
Mee-Kyung Chung ◽  
Paul Fancy ◽  
Jeffrey M Stryker
Keyword(s):  
Supramolecular Chemistry ◽  
Direct Synthesis ◽  
Protecting Groups ◽  
Tert Butyl ◽  
Orthogonal Protection ◽  
Protection Strategies ◽  
Titanium Trichloride ◽  
Sterically Hindered ◽  
Derivatives Of

The direct synthesis of sterically hindered, partially etherified derivatives of tetrakis(2-hydroxyphenyl)ethene is reported by using the McMurry reductive olefination reaction on a range of differentially substituted 2,2′-dialkoxy benzophenone substrates. Three orthogonal protection strategies are demonstrated, incorporating β-silylethyl, 3-butenyl, and tert-butyl protecting groups, respectively, into the starting benzophenones. The latter proved most efficient, with both the McMurry coupling and deprotection steps occurring concomitantly under the McMurry conditions to directly yield the desired bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene as a 1:1 mixture of E- and Z-diastereoisomers.Key words: preorganized polyaryloxide ligands, McMurry olefination, titanium trichloride, supramolecular chemistry, tetrakis(2-hydroxyphenyl)ethene, 2,2′-disubstituted benzophenone.

scholarly journals Synthesis and anticonvulsant activity of 6-methyl-2-((2-oxo-2-arylethyl)thio)pyrimidin-4(3 H)-one derivatives and products of their cyclization

Pharmacia ◽  
2019 ◽  
Vol 66 (3) ◽  
pp. 141-146
Author(s):  
Hanna Severina ◽  
Olga O. Skupa ◽  
Natalya I. Voloshchuk ◽  
Marharyta M. Suleiman ◽  
Victoriya A. Georgiyants
Keyword(s):  
Sulphuric Acid ◽  
Anticonvulsant Activity ◽  
Sodium Methoxide ◽  
Structure Activity ◽  
Phenacyl Bromides ◽  
Pharmacological Screening ◽  
High Yields ◽  
Derivatives Of

The alkylation of 6-methyl-2-thioxo-2,3-dihydro-1H-pyrimidine-4-one phenacyl bromides under different conditions was investigated. It was found that during the reaction in the medium of DMF/K2CO3 a mixture of 2-(2-aryl-2-oxoethyl)thio-6-methyl-pyrimidine-4(3H)-one and 3-hydroxy-3-aryl-7-methyl-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-5-one was formed. The holding of the resulting mixture in the concentrated sulphuric acid leads to the formation of cyclization products - derivatives of 3-aryl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-one with high yields. Individual S-alkylated derivatives – 2-(2-aryl-2-oxoethyl)thio-6-methyl-pyrimidine-4(3H)-one - were obtained by reacting in methanol in the presence of sodium methoxide. Pharmacological screening of synthesized compounds for anticonvulsant activity on the model of pentylenetetrazole seizures in rats was carried out and some regularity “structure-activity” was established.

Preparation and some biological properties of N-acetylmuramyl-alanyl-D-isoglutamine (MDP) analogues

1982 ◽  
Vol 47 (11) ◽  
pp. 2989-2995 ◽  
Author(s):  
Milan Zaoral ◽  
Jan Ježek ◽  
Jiří Rotta
Keyword(s):  
Biological Properties ◽  
Benzyl Ester ◽  
Protecting Groups

The condensation of 1-α-O-benzyl-4,6-O-benzylidene-N-acetylgalactomuramic acid (I), 1-α-O-benzyl-4,6-O-benzylidene-N-acetylallomuramic acid (VIII), and 1-α-O-benzyl-4,6-O-benzylidene-N-acetylnorallomuramic acid (XI) with alanyl-D-isoglutamine benzyl ester afforded 1-α-O-benzyl-4,6-O-benzylidene-N-acetylgalactomuramyl-alanyl-D-isoglutamine benzyl ester (XII), 1-α-O-benzyl-4,6-O-benzylidene-N-acetylallomuramyl-alanyl-D-isoglutamine benzyl ester (XIII) and 1-α-O-benzyl-4,6-O-benzylidene-N-acetylnorallomuramyl-alanyl-D-isoglutamine benzyl ester (XIV). Protecting groups were removed from XII-XIV and N-acetylgalactomuramyl-alanyl-D-isoglutamine (XV), N-acetylallomuramyl-alanyl-D-isoglutamine (XVI), and N-acetylnorallomuramyl-alanyl-D-isoglutamine (XVII) were obtained. XV-XVII showed lower pyrogenic and immunoadjuvant effect than N-acetylmuramyl-alanyl-D-isoglutamine.

scholarly journals Caffeic Acid Esters Are Effective Bactericidal Compounds Against Paenibacillus larvae by Altering Intracellular Oxidant and Antioxidant Levels

Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 312 ◽  
Author(s):  
William Collins ◽  
Noah Lowen ◽  
David J. Blake
Keyword(s):  
Caffeic Acid ◽  
Bacterial Growth ◽  
Bactericidal Effect ◽  
Caffeic Acid Phenethyl Ester ◽  
Benzyl Ester ◽  
Paenibacillus Larvae ◽  
Bacterial Disease ◽  
Bee Foraging ◽  
Caffeic Acid Esters ◽  
Acid Esters

American Foulbrood (AFB) is a deadly bacterial disease affecting pupal and larval honey bees. AFB is caused by the endospore-forming bacterium Paenibacillus larvae (PL). Propolis, which contains a variety of organic compounds, is a product of bee foraging and is a resinous substance derived from botanical substances found primarily in trees. Several compounds from the class of caffeic acid esters, which are commonly found in propolis, have been shown to have antibacterial activity against PL. In this study, six different caffeic acid esters were synthesized, purified, spectroscopically analyzed, and tested for their activity against PL to determine the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). Caffeic acid isopropenyl ester (CAIE), caffeic acid benzyl ester (CABE), and caffeic acid phenethyl ester (CAPE) were the most effective in inhibiting PL growth and killing PL cell with MICs and MBCs of 125 µg/mL when used individually, and a MIC and MBC of 31.25 µg/mL for each compound alone when CAIE, CABE, and CAPE are used in combination against PL. These compounds inhibited bacterial growth through a bactericidal effect, which revealed cell killing but no lysis of PL cells after 18 h. Incubation with CAIE, CABE, and CAPE at their MICs significantly increased reactive oxygen species levels and significantly changed glutathione levels within PL cells. Caffeic acid esters are potent bactericidal compounds against PL and eliminate bacterial growth through an oxidative stress mechanism.

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