Cyclizations of dialdehydes with nitromethane. XIV. The isolation of four crystalline methyl 3,6-dideoxy-3-nitro-α-L-hexopyranosides

1969 ◽  
Vol 47 (1) ◽  
pp. 99-103 ◽  
Author(s):  
Hans H. Baer ◽  
Karel Čapek
Keyword(s):  
Reaction Time ◽  
Catalytic Hydrogenation ◽  
Chromatographic Separation ◽  
Sodium Methoxide ◽  
Room Temperature ◽  
Total Yield

Cyclization of L′-methoxy-L-methyldiglycolic aldehyde (1) with nitromethane and sodium methoxide in methanol (40 min at room temperature) furnished four crystalline methyl 3,6-dideoxy-3-nitro-α-L-hexopyranosides in a combined yield of 75%. Chromatographic separation gave the gluco (2), manno (3), talo (4), and galacto (5) isomers in an approximate ratio of 18:8:3:1. Shortening of the reaction time to 25 min decreased the total yield to 53% at the expense of 2, the ratio of isolated products being 8:8:2.3:1.7. The configurations of the new nitro glycosides 3, 4, and 5 were proven by catalytic hydrogenation followed by N-acetylation, which gave the known 3-acetamido derivatives.

Über 5-Hydroxymethyl-cytidin und 5-Hydroxymethyl-cytosin-N-3-β-D-glucopyranosid sowie über reaktionsfähige Vorstufen

1966 ◽  
Vol 21 (10) ◽  
pp. 942-952 ◽  
Author(s):  
Reinhard Brossmer ◽  
Erich Röhm
Keyword(s):  
Hydrochloric Acid ◽  
Benzyl Alcohol ◽  
Catalytic Hydrogenation ◽  
Sodium Methoxide ◽  
Room Temperature ◽  
Selective Removal ◽  
Protecting Groups ◽  
Hydroxymethyl Cytosine ◽  
Analogous Manner ◽  
Synthetic Intermediates

5-Benzyloxymethyl-NNH2-benzoyl-cytosine (4) is formed from 5-hydroxymethyl-cytosine (1) in 80% yield by benzylation and subsequent benzoylation. The benzylation readily takes place with benzyl alcohol and catalytic amounts of hydrochloric acid in tetrahydrothiophen-1.1-dioxide as solvent. — 4 is quantitatively converted in pyridine at room temperature to a toluene soluble mercury (II) salt 5.5 condenses easily with 2.3.5-tribenzoyl-D-ribofuranosyl chloride to give the β-nucleoside 6, no a-anomer being found. — The removal of all protecting groups by catalytic hydrogenation and treatment with sodium methoxide or ammonia leads to cristalline 5-hydroxymethyl cytidine 10 (ca. 60% yields based on 1). — In an analogous manner N-3-β-D-glucosyl-5-hydroxymethyl-cytosine 15 is prepared. — Selective removal of certain of the protecting groups in 6 and 11 yields potentially valuable synthetic intermediates.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Facile room-temperature solution-phase synthesis of a spherical covalent organic framework for high-resolution chromatographic separation

2015 ◽  
Vol 51 (61) ◽  
pp. 12254-12257 ◽  
Author(s):  
Cheng-Xiong Yang ◽  
Chang Liu ◽  
Yi-Meng Cao ◽  
Xiu-Ping Yan
Keyword(s):  
High Resolution ◽  
Surface Area ◽  
Chromatographic Separation ◽  
Room Temperature ◽  
Solution Phase ◽  
Phase Synthesis ◽  
Covalent Organic Framework ◽  
Solution Phase Synthesis ◽  
Temperature Solution ◽  
Organic Framework

Facile room-temperature solution-phase synthesis of a spherical covalent organic framework with large surface area and good stability for high-resolution chromatographic separation.

Hypervalent Iodine(III)-Catalyzed Epoxidation of β-Cyanostyrenes

Synthesis ◽  
2019 ◽  
Vol 51 (23) ◽  
pp. 4473-4486 ◽  
Author(s):  
Saeesh R. Mangaonkar ◽  
Fateh V. Singh
Keyword(s):  
Reaction Time ◽  
Room Temperature ◽  
Hypervalent Iodine ◽  
Short Reaction Time ◽  
Convenient Approach

A convenient approach for the synthesis of β-cyanoepoxides is illustrated by iodine(III)-catalyzed epoxidation of electron-deficient β-cyanostyrenes, wherein the active catalytic iodine(III) species was generated in situ. The epoxidation of β-cyanostyrenes was performed using 10 mol% PhI as precatalyst in the presence of 2.0 equivalents Oxone as an oxidant and 2.4 equivalents of TFA as an additive at room temperature under ultrasonic radiations. The β-cyanoepoxides were isolated in good to excellent yields in a short reaction time.

The Research for Microwave Modified Vermiculite Adsorption of Zn2+

2014 ◽  
Vol 809-810 ◽  
pp. 493-499
Author(s):  
Li Fang Bao ◽  
Chen Li Wang ◽  
Jin Chuan Gu ◽  
Sheng Zhong ◽  
Rui Wang
Keyword(s):  
Reaction Time ◽  
Correlation Coefficient ◽  
Adsorption Isotherms ◽  
Reaction Temperature ◽  
Room Temperature ◽  
Adsorption Equilibrium ◽  
Adsorption Rate ◽  
Absorption Mechanism ◽  
Initial Concentration ◽  
The Impact

The impact on the adsorption of Zn2+of these factors, initial concentration, modification time, reaction time vermiculite dosage, reaction temperature and pH having, and absorption mechanism are studied . The results show that: microwave modification time 30s, reaction time 40min, modified vermiculite dosage 8g/L, reaction temperature 30°C, reaction pH 6, Zn2+ adsorption rate can reach 97.91%, adsorption isotherms of Zn2+ by microwave modified vermiculite show that the adsorption equilibrium is consistent with Langmuir curves, correlation coefficient reached to 0.997 at room temperature.

Desulfurization from Gasoline by Polymer Resin at Room Temperature and Atmospheric Pressure

2011 ◽  
Vol 396-398 ◽  
pp. 1283-1286
Author(s):  
Jian Peng Zhu ◽  
Chun Hu Li ◽  
Jia Ling Chen ◽  
Ying Wei Luo
Keyword(s):  
Reaction Time ◽  
Sulfur Content ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Oxidative Desulfurization ◽  
Sulfur Compounds ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Polymer Resin ◽  
Mild Conditions

Abstract. Investigation of polymer resin as catalyst in the oxidative desulfurization (ODS) process has revealed that the method can be applied to make a relative high removal of sulfur compounds. The reaction conditions, including temperature, amount of oxidant and reaction time were studied. The best result occurs under mild conditions with respect to room temperature and atmospheric pressure, to remove 75.54% of the totle sulfur content in the presence of H2O2 with an O/S molar ratio of 17. Possible mechanism is also disscussed.

Synthesis of Epihalohydrins by Dehydrohalogenation of Glycerol Dihalohydrins - Utilization of a Basic Ion-Exchange Resin

1992 ◽  
Vol 45 (8) ◽  
pp. 1327
Author(s):  
M Dargelos ◽  
ME Borredon ◽  
A Gaset
Keyword(s):  
Reaction Time ◽  
Ion Exchange ◽  
Room Temperature ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Organic Medium ◽  
Short Reaction Time ◽  
Hydrolysis Of

Dehydrohalogenation of a mixture of glycerol 1,3- and 2,3-dihalohydrins by a strong basic ion-exchange resin (IRA 440 and A 26) at room temperature in an organic medium quantitatively leads to the corresponding epihalohydrin (1a; X = Cl), and (1b; X = Br) in a very short reaction time. Hydrolysis of the epihalohydrin does not occur under these conditions.

scholarly journals Simple Protocol for the Knoevenagel Condensation Under Solvent Free Conditions using Tungstophosphoric Acid as Catalyst

2019 ◽  
Vol 31 (10) ◽  
pp. 2181-2184
Author(s):  
Abdulrahman I. Alharthi
Keyword(s):  
Catalytic Activity ◽  
Reaction Time ◽  
Room Temperature ◽  
Model Compound ◽  
Knoevenagel Condensation ◽  
Maximum Yield ◽  
Tungstophosphoric Acid ◽  
Grinding Method ◽  
Solvent Free Conditions ◽  
Simple Protocol

The effect of calcination on the performance of tungstophosphoric acid for the product of Knoevenagel condensation was investigated. Substituted aldehydes and dimedone has been used in the presence of calcined tungstophosphoric acid as a heterogeneous catalyst using grinding method at room temperature. The results of reactions revealed that calcined tungstophosphoric acid has superior catalytic activity comparing to non-calcined catalyst in terms of yield and reaction time. Maximum yield of model compound was achieved by using 10 mol% of calcined catalyst in a reaction time that does not exceed 10 min, whereas the yield at same amount of non-calcined catalyst was 86 % in a reaction time of 35 min.

Efficient Copper-Catalyzed Synthesis of Substituted Pyrazoles at Room Temperature

Synlett ◽  
2018 ◽  
Vol 29 (20) ◽  
pp. 2689-2692 ◽  
Author(s):  
Haifeng Wang ◽  
Xiangli Sun ◽  
Shuangling Zhang ◽  
Guanglu Liu ◽  
Chunjie Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Catalytic System ◽  
Efficient Method ◽  
Room Temperature ◽  
Copper Catalyst ◽  
Condensation Reaction ◽  
Reaction Conditions ◽  
Short Reaction Time ◽  
Acid Catalyzed ◽  
Substituted Pyrazoles

An efficient method for the synthesis of pyrazoles through a copper-catalyzed condensation reaction has been developed. The new catalytic system not only maintained a broad substrate scope but was also active under acid-free reaction conditions, overcoming the conventional requirement for an acid-catalyzed system. Furthermore, the copper catalyst enabled this reaction to be performed at room temperature and in a short reaction time.

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