scholarly journals Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

2014 ◽  
Vol 10 ◽  
pp. 1942-1950 ◽  
Author(s):  
Maroš Bella ◽  
Bohumil Steiner ◽  
Vratislav Langer ◽  
Miroslav Koóš
Keyword(s):  
Spectral Data ◽  
Crystallographic Analysis ◽  
Grignard Reaction ◽  
Reaction Conditions ◽  
X Ray

The Grignard reaction of 2,3-O-isopropylidene-α-D-lyxo-pentodialdo-1,4-furanoside and benzylmagnesium chloride (or bromide) afforded a non-separable mixture of diastereomeric benzyl carbinols and diastereomeric o-tolyl carbinols. The latter resulted from an unexpected benzyl to o-tolyl rearrangement. The proportion of benzyl versus o-tolyl derivatives depended on the reaction conditions. Benzylmagnesium chloride afforded predominantly o-tolyl carbinols while the application of benzylmagnesium bromide led preferably to the o-tolyl carbinols only when used in excess or at higher temperatures. The structures of the benzyl and o-tolyl derivatives were confirmed unambiguously by NMR spectral data and X-ray crystallographic analysis of their 5-ketone analogues obtained by oxidation of the corresponding mixture of diastereomeric carbinols. A possible mechanism for the Grignard reaction leading to the benzyl→o-tolyl rearrangement is also proposed.

The Meisenheimer rearrangement in heterocyclic synthesis. II. Synthesis and X-ray crystal structure of a tetrahydro-1H-2,3-benzoxazocine and preparation of a hexahydro-2,3-benzoxazonine

1980 ◽  
Vol 33 (6) ◽  
pp. 1323 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
PE Davies ◽  
CLWAH Raston
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Acetic Acid ◽  
Crystal And Molecular Structure ◽  
Phosphorus Oxychloride ◽  
Crystallographic Analysis ◽  
Heterocyclic Synthesis ◽  
Reaction Conditions ◽  
X Ray ◽  
Heterocyclic Derivatives

The heterocyclic derivatives, 8,9-dimethoxy-3-methyl-1-phenyl-3,4,5,6- tetrahydro-1H-2,3-benzoxazocine(3a) and 9,10-dimethoxy-3-methyl-1- phenyl-1,3,4,5,6,7-hexahydro-2,3-benzoxazonine (3b),examples of two new ring systems, have been prepared by Meisenheimer rearrangement of the corresponding 2-benzazepine and 2-benzazocine N-oxide derivatives (2a) and (2b). The Bischler-Napieralski-type cyclization reaction was used in the preparation of the tertiary amine precursors of these N-oxides reaction conditions for the cyclization were critical and phosphorus oxychloride in refluxing butanenitrile was found to give the best yields of the seven- or eight-membered cyclic imine intermediates. Reductive cleavage of the benzoxazocine derivative (3a) with zinc in acetic acid followed by N-methylation gave the expected product, [2-{3- (dimethylamino)propyl}-4,5-di-methoxyphenyl]phenylmethanol (12). The crystal and molecular structure of (3a) has been determined by X-ray crystallographic analysis.

scholarly journals A Novel 4α-Methyl Sterol from the Soft Coral Nephthea chabroli

1999 ◽  
Vol 23 (10) ◽  
pp. 628-629
Author(s):  
G. Mehta ◽  
Y. Venkateswarlu ◽  
M. Rama Rao ◽  
R. Uma
Keyword(s):  
Spectral Data ◽  
Soft Coral ◽  
Crystallographic Analysis ◽  
X Ray ◽  
Methyl Sterol

A new sterol, 4α-methyl-24-methylene-5α-cholestan-3β,8β-diol (1) and three known sterols 4α-methyl-24-methyl-enecholestan-3β-ol, 4α-methylcholestan-3β-ol and 24-methylenecholest-4-en-3-one are isolated from the soft coral Nephthea chabroli and characterized through spectral data and in the case of 1 by X-ray crystallographic analysis.

A Facile and Convenient Approach for the Synthesis of Novel Sesamol–Oxazine and Quinoline–Oxazine Hybrids

2017 ◽  
Vol 70 (12) ◽  
pp. 1285 ◽  
Author(s):  
Garima Khanna ◽  
Pooja Saluja ◽  
Jitender M. Khurana
Keyword(s):  
Spectral Data ◽  
Aromatic Amines ◽  
Reaction Times ◽  
The Novel ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Convenient Approach ◽  
High Yields ◽  
Operational Simplicity

A series of functionalized sesamol–oxazine and quinoline–oxazine hybrids have been synthesized via one-pot reaction of sesamol/6-hydroxyquinoline, aromatic amines, and methanal. The structures of all the novel compounds were confirmed by spectral data. The structures of the synthesized hybrids were also confirmed by X-ray crystallographic studies. Mild reaction conditions, operational simplicity, short reaction times, simple workup, and high yields of products are salient features of this methodology.

KI-catalyzed synthesis of S-Thiocarbamates by cross-coupling of cyclohexyl isocyanide with sulfonyl chlorides

2019 ◽  
Vol 43 (9-10) ◽  
pp. 347-351
Author(s):  
Liangwei Lin ◽  
Zhengjun Fang ◽  
Yajun Li ◽  
Feng Wu ◽  
Chaktong Au ◽  
...  
Keyword(s):  
Functional Group ◽  
High Resolution Mass Spectrometry ◽  
Cross Coupling ◽  
Crystallographic Analysis ◽  
Resonance Spectroscopy ◽  
Reaction Conditions ◽  
Sulfonyl Chlorides ◽  
X Ray ◽  
Direct Generation ◽  
Resolution Mass

A simple and efficient process for direct generation of various S-thiocarbamates is developed by cross-coupling of readily available sulfonyl chlorides with cyclohexyl isocyanide. The yields are excellent and the structures of the generated S-thiocarbamates are characterized by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and high-resolution mass spectrometry together with X-ray crystallographic analysis. The protocol has the advantages of using easily available reagents, employs inexpensive KI as the reagent, demonstrates good functional group tolerance, and utilizes mild reaction conditions.

Synthesis and structures of [2n](2,7)naphthalenophanes (n = 2–4)

2017 ◽  
Vol 95 (4) ◽  
pp. 445-449 ◽  
Author(s):  
Kenta Ohtsuka ◽  
Guangke Cai ◽  
Kazuya Fujita ◽  
Hirokazu Miyoshi ◽  
Yoshito Tobe
Keyword(s):  
Uv Spectra ◽  
Crystallographic Analysis ◽  
Reductive Coupling ◽  
Reaction Conditions ◽  
X Ray

Reductive coupling of 2,7-bis(bromomethyl)naphthalene using phenyllithium gave anti-[22](2,7)naphthalenophane, [23](2,7)naphthalenophane, and [24](2,7)naphthalenophane, the distribution of which was dependent on the reaction conditions. The structure of the first compound was established by X-ray crystallographic analysis. On the basis of the similarity between the NMR and UV spectra of [23](2,7)naphthalenophane with those reported for syn-[22](2,7)naphthalenophane, we conclude that the compound originally assigned to be syn-4 was in fact 6.

Alkaloids from Papaver setigerum DC.

1996 ◽  
Vol 61 (7) ◽  
pp. 1047-1052 ◽  
Author(s):  
Jiří Slavík ◽  
Leonora Slavíková
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Spectral Data ◽  
Crystallographic Analysis ◽  
Minor Constituents ◽  
X Ray ◽  
Benzylisoquinoline Alkaloids ◽  
Layer Chromatography

Two new benzylisoquinoline alkaloids of the papaverine type, setigerine (racemic α-methoxypapaverine, 1b) and setigeridine (1c), were isolated from Papaver setigerum DC. as the minor constituents. Their structures were established by spectral data and X-ray crystallographic analysis. Papaverine (1a) was isolated as the major alkaloid of the plant (0.05 wt.%) besides of less amounts of morphine, codeine and rhoeadine. In a low yield, protopine, cryptopine, thebaine, rhoeagenine, and N-methylthebainium (as iodide) were obtained and small quantities of laudanosine, stylopine, isoboldine, scoulerine, papaverrubine A, B, C, D and E, coptisine, corytuberine, and magnoflorine were identified by thin layer chromatography.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Purification, crystallization and X-ray crystallographic analysis of ATPase domain in transcription regulator DmpR

2019 ◽  
Vol 7 (2) ◽  
pp. 52-55
Author(s):  
Su-Jin Lee ◽  
In-Young Baek ◽  
Yan An ◽  
Woo-Chan Ahn ◽  
Kwang-Hyun Park ◽  
...  
Keyword(s):  
Crystallographic Analysis ◽  
Atpase Domain ◽  
X Ray ◽  
Transcription Regulator

Purification, crystallization and X-ray crystallographic analysis of methylglyoxal reductase Gre2 from Candida albicans

2019 ◽  
Vol 7 (2) ◽  
pp. 42-46 ◽  
Author(s):  
Giang Thu Nguyen ◽  
Shinae Kim ◽  
Hang-Suk Chun ◽  
Woo-Keun Kim ◽  
Jeong Ho Chang
Keyword(s):  
Candida Albicans ◽  
Crystallographic Analysis ◽  
X Ray
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