Convergent Routes to the [1,3]Dioxolo[4,5-j]phenanthridin-6(5H)-one and 2,3,4,4a-Tetrahydro[1,3]dioxolo[4,5-j]phenanthridin-6(5H)-one Nuclei. Application to Syntheses of the Amaryllidaceae Alkaloids Crinasiadine, N-Methylcrinasiadine and Trisphaeridine

1994 ◽  
Vol 47 (12) ◽  
pp. 2235 ◽  
Author(s):  
MG Banwell ◽  
CJ Cowden
Keyword(s):  
Boronic Acid ◽  
Ring Opening ◽  
Phosphorus Oxychloride ◽  
Suzuki Coupling ◽  
The Other ◽  
Aryl Bromide ◽  
Amaryllidaceae Alkaloids ◽  
Reaction Proceeds ◽  
Compound Ii ◽  
Hydrolysis Of

Convergent routes to the title nuclei, (1) and (6), have been developed. Thus, Suzuki coupling of boronic acid (8) with aryl bromide (9) gave the biarylylcarbamate (7) which, on treatment with phosphorus oxychloride (POCl3), underwent Bischler-Napieralski cyclization to give, after acid hydrolysis, the Amaryllidaceae alkaloid crinasiadine (1). The cyclization reaction proceeds via an intermediate chlorophenanthridine (11) which can be isolated and N- methylated. Hydrolysis of the resulting iminium species (17) then afforded N- methylcrinasiadine (2). On the other hand, hydrogenolytic dechlorination of compound (II) affords trisphaeridine (14). Related chemistry has been employed in the preparation of 2,3,4,4a-tetrahydro[1,3] dioxolo [4,5-j]phenanthridin-6(5H)-one (6), the tetracyclic skeleton associated with the narcissus alkaloids lycoricidine (3) and narciclasine (4). Thus, treatment of the gem- dibromocyclopropane (20) with silver cyanate resulted in ring opening thereby affording the allylic isocyanate (25) which could be intercepted with added methanol to give carbamate (24). Suzuki coupling of this last compound with boronic acid (8) gave product (18) which was subjected to treatment with and resulted in the formation of (�)-(6). This latter sequence could be adapted to the preparation of both (R)-(6) and (S)-(6).

scholarly journals A magnetically retrievable mixed-valent Fe3O4@SiO2/Pd0/PdII nanocomposite exhibiting facile tandem Suzuki coupling/transfer hydrogenation reaction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Parminder Singh ◽  
Saumyaranjan Mishra ◽  
Anupam Sahoo ◽  
Srikanta Patra
Keyword(s):  
Electron Microscopy ◽  
Boronic Acid ◽  
Suzuki Coupling ◽  
Hydrogenation Reaction ◽  
Transfer Hydrogenation ◽  
Aryl Bromide ◽  
Nanocomposite System ◽  
Transfer Hydrogenation Reaction ◽  
Catalytic Cycles ◽  
Aryl Boronic Acid

AbstractHerein, we report a magnetically retrievable mixed-valent Fe3O4@SiO2/Pd0/PdIINP (5) nanocomposite system for tandem Suzuki coupling/transfer hydrogenation reaction. The nanocomposite 5 was prepared first by making a layer of $$\hbox {SiO}_{2}$$ SiO 2 on $$\hbox {Fe}_{3}\hbox {O}_{4}\hbox {NP}$$ Fe 3 O 4 NP followed by deposition of $$\hbox {Pd}^{0}$$ Pd 0 and sorption of $$\hbox {Pd}^{\mathrm{II}}$$ Pd II ions successively onto the surface of Fe3O4@SiO2NP. The nanocomposite was characterized by powder XRD, electron microscopy (SEM-EDS and TEM-EDS) and XPS spectroscopy techniques. The mixed-valent $$\hbox {Pd}^{0}/\hbox {Pd}^{\mathrm{II}}$$ Pd 0 / Pd II present onto the surface of nanocomposite 5 was confirmed by XPS technique. Interestingly, the mixed-valent nanocomposite Fe3O4@SiO2/Pd0/PdIINP (5) exhibited tandem Suzuki coupling/transfer hydrogenation reaction during the reaction of aryl bromide with aryl boronic acid (90% of C). The nanocomposite 5 displayed much better reactivity as compared to the monovalent Fe3O4@SiO2/Pd0NP (3) (25% of C) and Fe3O4@SiO2/PdIINP (4) (15% of C) nanocomposites. Further, because of the presence of magnetic $$\hbox {Fe}_{3}\hbox {O}_{4}$$ Fe 3 O 4 , the nanocomposite displayed its facile separation from the reaction mixture and reused at least for five catalytic cycles.

ORGANIC PHOSPHORUS COMPOUNDS: II: PREPARATION OF CHLOROMETHANEPHOSPHONYL DICHLORIDE

1953 ◽  
Vol 31 (10) ◽  
pp. 976-983 ◽  
Author(s):  
R. A. B. Bannard ◽  
J. R. Gilpin ◽  
G. R. Vavasour ◽  
A. F. McKay
Keyword(s):  
Atmospheric Pressure ◽  
Phosphorus Oxychloride ◽  
Organic Phosphorus ◽  
Phosphorus Pentachloride ◽  
Heating Time ◽  
Phosphorus Trichloride ◽  
The Other ◽  
Phosphorus Compounds ◽  
Subsequent Hydrolysis ◽  
Hydrolysis Of

Hydroxymethanephosphonic acid was prepared by treating paraformaldehyde with phosphorus trichloride at atmospheric pressure and subsequent hydrolysis of the resultant complex. Chloromethanephosphonyl dichloride was obtained by chlorination of hydroxymethanephosphonic acid with thionyl.chloride in the presence of pyridine. On the other hand hydroxymethanephosphonic acid combined slowly with phosphorus pentachloride to give the hitherto unknown dichlorophosphorylmethanephosphonyl dichloride, Cl2P(O)OCH2P(O)Cl2, together with chloromethanephosphonyl dichloride. The structure of dichlorophosphorylmethanephosphonyl dichloride was confirmed by its conversion with phosphorus pentachloride at 78 °C into chloromethanephosphonyl dichloride and phosphorus oxychloride. The preparation of chloromethanephosphonyl dichloride by interaction of paraformaldehyde and phosphorus trichloride in an autoclave at 250 °C was studied in reference to the influence of heating time on the yield.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

2019 ◽  
Author(s):  
Marharyta V. Laktsevich-Iskryk ◽  
Nastassia A. Varabyeva ◽  
Volha V. Kazlova ◽  
Vladimir N. Zhabinskii ◽  
Vladimir A. Khripach ◽  
...  
Keyword(s):  
Visible Light ◽  
Functional Groups ◽  
Ring Opening ◽  
Radical Intermediates ◽  
Reaction Proceeds

In this article, we report a photocatalytic protocol for the isomerization of 1,2-disubstituted cyclopropanols to linear ketones. The reaction proceeds <i>via</i> radical intermediates and tolerates various functional groups.

Visible Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones

2019 ◽  
Author(s):  
Marharyta V. Laktsevich-Iskryk ◽  
Nastassia A. Varabyeva ◽  
Volha V. Kazlova ◽  
Vladimir N. Zhabinskii ◽  
Vladimir A. Khripach ◽  
...  
Keyword(s):  
Visible Light ◽  
Functional Groups ◽  
Ring Opening ◽  
Radical Intermediates ◽  
Reaction Proceeds

In this article, we report a photocatalytic protocol for the isomerization of 1,2-disubstituted cyclopropanols to linear ketones. The reaction proceeds <i>via</i> radical intermediates and tolerates various functional groups.

Construction the A-B bicyclic ring structure of Stemocurtisisne

2020 ◽  
Vol 17 ◽  
Author(s):  
Duc Dau Xuan
Keyword(s):  
Glutamic Acid ◽  
Natural Product ◽  
Mannich Reaction ◽  
Boronic Acid ◽  
Ring Opening ◽  
Ring Structure ◽  
Starting Material ◽  
Epoxide Ring ◽  
Epoxide Ring Opening

: The synthesis of the A-B bicyclic ring structure 3 of the natural product Stemocurtisine is described. The synthesis was accomplished in seven synthetic steps from commercially available L-glutamic acid. The key step involved a borono-Mannich reaction between the hemiaminal 6 and trans-β-styryl boronic acid and trans-β-styrylpotassiumtrifluoroborate to prepare the cis diene 4. Attempts to prepare the A-B-C ring compound 2 via intramolecular epoxide ring opening followed by rearangement under different basic conditions were unsuccessful. Only unreactive starting material was recovered.

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

THE ALDOBIOURONIC ACIDS OF HEMICELLULOSE B OF OAT HULLS

1956 ◽  
Vol 34 (3) ◽  
pp. 338-344 ◽  
Author(s):  
E. L. Falconer ◽  
G. A. Adams
Keyword(s):  
Glucuronic Acid ◽  
The Other ◽  
Partial Hydrolysis ◽  
Oat Hulls ◽  
Hydrolysis Of

Partial hydrolysis of hemicellulose B from oat hulls yielded two aldobiouronic acids, which were identified as 2-O-(4-O-methyl-α-D-glucopyruronosyl)-D-xylose and 2-O-(α-D-glucopyruronosyl)-D-xylose respectively. In addition, two aldotriouronic acids were isolated, one yielding on hydrolysis xylose and 4-O-methyl-glucuronic acid, and the other, xylose, galactose, and glucurone.

scholarly journals DABCO Catalyzed Synthesis of Xanthene Derivatives in Aqueous Media

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Pradeep Paliwal ◽  
Srinivasa Rao Jetti ◽  
Anjna Bhatewara ◽  
Tanuja Kadre ◽  
Shubha Jain
Keyword(s):  
Reaction Time ◽  
Aqueous Media ◽  
Environmentally Friendly ◽  
The Other ◽  
Short Reaction Time ◽  
Xanthene Derivatives ◽  
Reaction Proceeds ◽  
Conventional Methods

The reaction of 5,5-dimethylcyclohexane-1,3-dione with various heteroarylaldehydes afforded the corresponding heteroaryl substituted xanthene derivatives 1(a–f). The reaction proceeds via the initial Knoevenagel, subsequent Michael, and final heterocyclization reactions using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst in aqueous media. The synthesized heteroaryl substituted xanthenes 1(a–f) reacted with malononitrile to obtain different alkylidenes 2(a–f). Short reaction time, environmentally friendly procedure, avoiding of cumbersome apparatus, and excellent yields are the main advantages of this procedure which makes it more economic than the other conventional methods.

A synthesis and some reactions of 7-Oxabicyclo[2.2.1]heptan-2-one

1983 ◽  
Vol 36 (12) ◽  
pp. 2473 ◽  
Author(s):  
J Moursounidis ◽  
D Wege
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acid Mixture ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Atom Migration ◽  
Acyl Azide ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro-and endo-2-chloro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile (4) and (5). Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation. Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of a-chloro isocyanates yields 7-oxabicyclo[2.2.l]heptan-2-one (1) in preparatively useful amounts. Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration. Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo[2.2.1 .02,6]heptane.

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