o-Nitrophenylethylene glycol as photoremovable protective group for aldehydes and ketones: syntheses, scope, and limitations

1983 ◽  
Vol 61 (2) ◽  
pp. 400-410 ◽  
Author(s):  
D. Gravel ◽  
J. Hebert ◽  
D. Thoraval
Keyword(s):  
Point Of View ◽  
High Yield ◽  
Protective Group ◽  
Isolation And Characterization ◽  
Usual Manner ◽  
Aldehydes And Ketones ◽  
Inert Solvent ◽  
Acidic Conditions ◽  
High Yields

The preparation of o-nitrophenylethylene glycol is described along with its application as a photolabile protective group for aldehydes and ketones. Formation of the acetals and ketals is achieved in good to high yields in the usual manner and deprotection is carried out in fair to high yield, by photolysis at 350 nm in an inert solvent such as benzene. Because of the particular nature of the present protective group, its stability to basic and acidic conditions has been examined and is reported to complete the scope and limitations aspect. From a mechanistic point of view, the isolation and characterization of o-nitroso-α-hydroxyacetophenone as the spent reagent demonstrates a mechanistic link with the known o-nitrobenzaldehyde to o-nitrosobenzoic acid photorearrangement.

scholarly journals The copolymeric structure of pig skin dermatan sulphate. Isolation and characterization of l-idurono-sulphate-containing oligosaccharides from copolymeric chains

1974 ◽  
Vol 143 (2) ◽  
pp. 379-389 ◽  
Author(s):  
Lars-Åke Fransson ◽  
Lars Cöster ◽  
Birgitta Havsmark ◽  
Anders Malmström ◽  
Ingrid Sjöberg
Keyword(s):  
Periodate Oxidation ◽  
Exchange Chromatography ◽  
Dermatan Sulphate ◽  
Chondroitinase Abc ◽  
Pig Skin ◽  
Isolation And Characterization ◽  
Smith Degradation ◽  
Iduronic Acid ◽  
Acidic Conditions

Dermatan sulphate was degraded by testicular hyaluronidase and an oversulphated fraction was isolated by ion-exchange chromatography. This preparation, which contained fairly long segments derived from the non-reducing terminal portion of the molecule, was subjected to periodate oxidation under acidic conditions. The oxidized iduronic acid residues were cleaved by reduction-hydrolysis (Smith-degradation) (Fransson & Carlstedt, 1974) or by alkaline elimination. The oligosaccharides so obtained contained both GlcUA (glucuronic acid) and IdUA-SO4 (sulphated iduronic acid) residues. Copolymeric oligosaccharides obtained after alkaline elimination were cleaved by chondroitinase-AC into disaccharide and higher oligosaccharides. Since the corresponding oligosaccharides obtained by Smith-degradation were unaffected by this enzyme, it was concluded that the carbohydrate sequences were GalNAc-(IdUA-GalNAc)n-GlcUA-GalNAc. The iduronic acid-containing sequences were resistant to digestion with chondroitinase-ABC. It was demonstrated that the presence of unsulphated N-acetylgalactosamine residues in these sequences could be responsible for the observed effect. This information was obtained in an indirect way. Chemically desulphated dermatan sulphate was found to be a poor substrate for the chondroitinase-ABC enzyme. Moreover, digestion with chondroitinase-ABC of chondroitinase-AC-degraded dermatan sulphate released periodate-resistant iduronic acid-containing oligosaccharides. It is concluded that copolymeric sequences of the following structure are present in pig skin dermatan sulphate: [Formula: see text] N-acetylgalactosamine moieties surrounding IdUA-SO4 residues are unsulphated to a large extent.

Nine- and Eight-Vertex Polyhedral Dicarbaborane Chemistry: New arachno and hypho Dicarbaboranes from arachno-4,5-C2B7H13: Isolation and Characterization of the [arachno-4,5-C2B7H12]- and [hypho-7,8-C2B6H13]- Anions, and of the Neutral Ligand Derivatives exo-6-(MeNC)-arachno-4,5-C2B7H11 and exo-5-L-hypho-4,9-C2B7H13 (L = NMe3 and NEt3)

1994 ◽  
Vol 59 (7) ◽  
pp. 1584-1595 ◽  
Author(s):  
Tomáš Jelínek ◽  
Josef Holub ◽  
Bohumil Štíbr ◽  
Xavier L. R. Fontaine ◽  
John D. Kennedy
Keyword(s):  
Nmr Spectroscopy ◽  
Selective Removal ◽  
High Yield ◽  
Two Dimensional ◽  
Neutral Ligand ◽  
Tertiary Amines ◽  
Proton Sponge ◽  
H Nmr ◽  
Isolation And Characterization

Deprotonation of neutral arachno-4,5-C2B7H13 (1) either with 1, 8-(NMe2)2C10H6 (proton sponge, PS) or with a mixture of aqueous K2CO3 and [NMe4]Cl leads to the isolation in high yield of the [arachno-4,5-C2B7H12]- anion (2). Isostructural with this anion is the ligand derivative exo-6-(MeNC)-arachno-4,5-C2B7H11 (3), which is prepared in 20% yield from the reaction between arachno-4,5-C2B7H13 and MeNC in dichloromethane. Under comparable conditions compound 1 with tertiary amines gives the first representatives of the nine-vertex hypho family of dicarbaboranes, the ligand derivatives exo-5-(NR3)-hypho-4,9-C2B7H13 (4a and 4b, where R = Me and Et, respectively) in moderate yields (20 - 55%), whereas the reaction between 1 and aqueous NaCN results in the selective removal of one boron vertex to yield the eight-vertex [hypho-7,8-C2B6H13]- anion (5) in 61% yield. All compounds isolated were characterized by 11B and 1H NMR spectroscopy, with two-dimensional and selective decoupling techniques giving unambiguous assignments.

scholarly journals A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

2009 ◽  
Vol 5 ◽  
Author(s):  
Andrew Bogdan ◽  
D Tyler McQuade
Keyword(s):  
Packed Bed ◽  
Secondary Alcohols ◽  
Great Stability ◽  
Wide Range ◽  
Oxidation Of Alcohols ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
By Products ◽  
Over Time

We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity.

scholarly journals Synthesis and Characterization of Novel 1,3-Thiazole and 2-Amino-1,3,4-Thiadiazole Derivatives

2014 ◽  
Vol 33 (2) ◽  
pp. 189 ◽  
Author(s):  
Mustafa Er ◽  
Ayşe Şahin ◽  
Hakan Tahtacı
Keyword(s):  
Biological Activities ◽  
High Yield ◽  
Synthesis And Characterization ◽  
Hantzsch Reaction ◽  
H Nmr ◽  
Thiadiazole Derivatives ◽  
High Yields ◽  
Mass Spectrometric Techniques ◽  
C Nmr

<p>Thiosemicarbazone derivatives <strong>3a–e</strong> were synthesized by the reaction of various aldehydes<strong> 1a–e</strong> with 4-methyl thiosemicarbazide <strong>2</strong> in 78% to 90% yield. Then, the thiazole moieties of the target materials <strong>5a–e</strong> were obtained in high yields (71–93%) using the Hantzsch reaction utilizing thiosemicarbazone derivatives <strong>3a–e</strong> with ethyl-2-chloroacetoacetic ester. The substituted nitrile derivatives <strong>7a–e</strong> were obtained in moderate to high yield (58–84%) from the reaction of compounds <strong>5a–e</strong> with chloroacetonitrile by the nucleophilic aliphatic substitution reaction in the presence of anhydrous potassium carbonate. Finally, substituted 2-amino-1,3,4-thiadiazole compounds <strong>9a–e</strong> were obtained in moderate to good yields (51–62%) from the reaction of thiosemicarbazide with substituted nitrile derivatives <strong>7a–e</strong>. As a result, compounds that all share a high disposition for biological activities were obtained. The structures of the newly synthesized compounds were confirmed by IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, elemental analysis, and mass spectrometric techniques.</p>

Isolation and characterization of glioblastoma nuclei and chromosomes in the lyophilized state

1971 ◽  
Vol 34 (3) ◽  
pp. 301-309 ◽  
Author(s):  
Wolff M. Kirsch ◽  
Demoy Schulz ◽  
Paul Nakane ◽  
Robert Lasher ◽  
Tadami Yamamoto
Keyword(s):  
Water Soluble ◽  
High Yield ◽  
Nonaqueous Media ◽  
Biosynthetic Activity ◽  
Content Type ◽  
Isolation And Characterization ◽  
Subcellular Organelle ◽  
Fine Print

✓ Intact lyophilized nuclei and chromosomes were obtained from glioblastomas or brain, either in situ or in culture, by freezing at −156°C, drying at −25°C, and mechanical disassociation in glycerol at 2°C. Nuclear or chromosomal isolation was accomplished in hygroscopic nonaqueous media of high density. The method gave homogeneous nuclear and chromosomal preparations in high yield with preservation of labile, water-soluble constituents and residual biosynthetic activity. Unique opportunities for quantitative cytochemical studies at the level of the subcellular organelle are made available by the method.

Isolation and Characterization of the Photoalteration Products of cis- and trans-Chlordane

1975 ◽  
Vol 58 (1) ◽  
pp. 6-9
Author(s):  
Francis I Onuska ◽  
Michael E Comba
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Thin Layer ◽  
High Yield ◽  
Isolation And Characterization ◽  
The Individual ◽  
Cis And Trans ◽  
Layer Chromatography

Abstract Ultraviolet irradiation of cis- and trares-chlordane yielded 3 photolysis products. The expected half-caged analog of cis-chlordane was formed in high yield, and 2 minor photoproducts of trans-chlordane were observed. One of these products was a half-caged isomer. The individual photoproducts were isolated by thin layer chromatography and characterized by infrared, nuclear magnetic resonance, and mass spectrometry.

scholarly journals Agro-morphological diversity of traditional fig cultivars grown in central-western Spain

Genetika ◽  
2016 ◽  
Vol 48 (2) ◽  
pp. 533-546 ◽  
Author(s):  
Rodrigo Pérez-Sánchez ◽  
Remedios Morales-Corts ◽  
Ángeles Gómez-Sánchez
Keyword(s):  
Genetic Resources ◽  
Plant Genetic Resources ◽  
Principal Component ◽  
Morphological Diversity ◽  
Point Of View ◽  
Synonymies And Homonymies ◽  
New Varieties ◽  
Western Spain ◽  
High Yields

There are not many exhaustive works addressing the agromorphological characterization of traditional fig (Ficus carica L.) cultivars in Spain. In order to analyze the diversity of these fig genetic resources, twelve traditional fig cultivars from the Central-Western Region of Spain were surveyed and characterized agromorphologically. A total of forty descriptors, mainly defined by the International Plant Genetic Resources Institute and the International Union for the Protection of New Varieties of Plants, were used to describe the fruits, leaves and the tree itself over two consecutive years (2013-2014). Some of the cultivars showed distinctive and interesting agronomical characters from a commercial point of view, such as two crops per year (breba and fig), high yields, and fruit quality. This was the case of the fig cultivar widely distributed through the Duero river valley called ?Cuarter?n?. Its fruits were quite heavy and sweet (breba: 93.75 g and 25.91? Brix; fig: 42.41 g and 31.50? Brix), easy to peel, and juicy. Principal component analysis revealed that more than 67% of the agromorphological variability observed was explained by the first three components, some of the breba size parameters (fruit and neck length and fruit width) being the most important factors in differentiating the genotypes. A dendrogram clustered the cultivars into two major groups (unifera and bifera type) and revealed existing synonymies and homonymies. ?Carballar Negra? and ?Moscatel? were the only fig cultivars which did not have breba crops. This work is an important step in the conservation of genetic fig resources in Spain.

scholarly journals Isolation and Characterization of Isorhamnetin and Kaempferol from Elaeagnus Angustifolia (F:Elaeagnaceae) Cultivated in Iraq

2019 ◽  
pp. 12-21
Keyword(s):  
Point Of View ◽  
Elaeagnus Angustifolia ◽  
Crystalline Powder ◽  
Isolation And Purification ◽  
Spectral Identification ◽  
Isolation And Characterization ◽  
Calcium Magnesium ◽  
Ft Ir ◽  
Iron And Manganese

Elaeagnus angustifolia, is from Elaeagnus genus and a member of the Elaeagnaceae family which is reported to have many species that are distributed throughout the world. The plant acquired a considerable importance because it is a rich source of vitamins such as tocopherol, carotene, vitamin C, thiamine B1 and minerals like calcium, magnesium, potassium, iron and manganese. from the phytochemical point of view, the plant was reported to contains: flavonoids, alkaloids, terpens, sterols and saponin. TLC fingerprinting was used to identify the ethyl acetate extract containing flavonoids. The isolation and purification afforded crystalline powder which were subjected to spectral identification by1H‐NMR and FT-IR. The compounds were identified as Isorhamnetin and Kaempferol.

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