PERFLUOROALKYL ARSENICALS: PART IX. SOME REACTIONS OF COMPOUNDS CONTAINING As–As BONDS

1964 ◽  
Vol 42 (5) ◽  
pp. 1123-1129 ◽  
Author(s):  
W. R. Cullen ◽  
N. K. Hota
Keyword(s):  
Ultraviolet Irradiation ◽  
Major Product ◽  
Mild Conditions ◽  
Cis And Trans

Arsenobenzene reacts with CF3I to give C6H5As(CF3)2, C6H5As(CF3)I, and C6H5AsI2. C6H5As(CF3)I and AgCl yield C6H5As(CF3)Cl. The compounds CF2=CFX react with (CH3)2As—As(CH3)2 under mild conditions to give 1:1 adducts (CH3)As—CF2CFX—As(CH3)2 (X = CF3, Br). Some (CH3)2As—CF=CF2 is produced when X = Br and is the major product when X = I. When X = F a 1:4 adduct (CH3)2As—(CF2CF2)4—As(CH3)2 is probably formed on ultraviolet irradiation. (CH3)2As—As(CH3)2 reacts with CF3C≡CCF3 to give cis and trans (CH3)2AsC(CF3)=C(CF3)As(CH3)2 and with [Formula: see text] to give (CH3)2AsF and [Formula: see text].

Dimethylplatinum(IV) Complexes With Cyanide: Thermal and Photoassisted Substitution Reactions, and Characterization of Products by N.M.R.

1987 ◽  
Vol 40 (9) ◽  
pp. 1565 ◽  
Author(s):  
TG Appleton ◽  
JR Hall ◽  
MA Williams
Keyword(s):  
Ultraviolet Irradiation ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Methyl Groups ◽  
Substitution Reactions ◽  
Aqueous Acid ◽  
Cyanide Ligands ◽  
Cis And Trans ◽  
Insoluble Precipitate

Reactions of cyanide with the dimethylplatinum (IV) complexes, [PtMe2(OH) (H20)1.5 n, [PtMe2Br2]n and fac-PtMe2Br(H2O)3+, have been studied, principally by 1H, 13C and 195Pt n.m.r. Cyanide rapidly displaces the ligands trans to the methyl groups. Subsequent reactions cis to the methyl groups occur more slowly with heating, or, for bromo complexes, on ultraviolet irradiation. These substitution reactions compete with reductive elimination of groups from the platinum(IV) compounds to produce platinum(II) products. All attempts to prepare solutions of fac-PtMe2(CN)(H2O)3+ were unsuccessful. Oxidative addition of ICN to cis-PtMe2( py )2 ( py = pyridine) gave PtMe2I(CN)( py )2, from which a solution of fac-PtMe2(CN)( MeOH )3+ in methanol could be obtained. Addition of water or aqueous acid to this solution gave a very insoluble precipitate of [PtMe2(CN)(OH)n. The cis and trans influences on Jpt -C and δC of the cyanide ligands have been evaluated.

Photo-additions of aromatic hydrocarbons—indene and naphthalene with acrylonitrile

1969 ◽  
Vol 47 (5) ◽  
pp. 757-766 ◽  
Author(s):  
John J. McCullough ◽  
C. W. Huang
Keyword(s):  
Butyl Alcohol ◽  
Major Product ◽  
Minor Amount ◽  
Strong Base ◽  
Magnetic Resonance Data ◽  
Cis And Trans Isomers ◽  
Resonance Data ◽  
Ethanol Yields ◽  
A Minor ◽  
Cis And Trans

The photolyses of indene and naphthalene with acrylonitrile have been studied, and the products characterized. Indene reacts with acrylonitrile when the hydrocarbon absorbs light, or when a triplet sensitizer (acetophenone) is absorbing. Photolysis under the former conditions in ethanol yields 2-(1-indenylpropionitrile) (70%), 2-(3-indenylpropionitrile) (10%), and 6-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene (20%). Base-catalyzed isomerizations of the substituted indenes are reported. On sensitization, cis- and trans-isomers of 7-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene are formed, with a minor amount of indene dimer. The former isomers can be equilibrated with strong base. Adducts of 1,1-dimethyl- and 1,1-diphenylindene with acrylonitrile are also described, and nuclear magnetic resonance data reported. Naphthalene adds acrylonitrile on photolysis in t-butyl alcohol (pyrex filter) to afford trans-8-cyano-2,3-benzobicyclo-[4,2,0]-octa-2,4-diene (90%) and 1- and 2-naphthyl-2-propionitrile (10%). Sensitization with acetophenone gave no detectable products. Irradiation of the major product at 253.7 mμ through Vycor gave naphthalene. The preparative value of these reactions is considered and possible mechanisms are proposed.

scholarly journals Synthesis and HPLC-ECD Study of Cytostatic Condensed O,N-Heterocycles Obtained from 3-Aminoflavanones

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1462
Author(s):  
Ádám Szappanos ◽  
Attila Mándi ◽  
Katalin Gulácsi ◽  
Erika Lisztes ◽  
Balázs István Tóth ◽  
...  
Keyword(s):  
Cell Lines ◽  
Absolute Configuration ◽  
Major Product ◽  
Acid Ceramidase ◽  
Substitution Pattern ◽  
Aryl Group ◽  
Ic50 Values ◽  
The Absolute ◽  
Cis And Trans ◽  
Condensed Heterocycles

Racemic chiral O,N-heterocycles containing 2-arylchroman or 2-aryl-2H-chromene subunit condensed with morpholine, thiazole, or pyrrole moieties at the C-3-C-4 bond were synthesized with various substitution patterns of the aryl group by the cyclization of cis- or trans-3-aminoflavanone analogues. The 3-aminoflavanone precursors were obtained in a Neber rearrangement of oxime tosylates of flavanones, which provided the trans diastereomer as the major product and enabled the isolation of both the cis- and trans-diastereomers. The cis- and trans-aminoflavanones were utilized to prepare three diastereomers of 5-aryl-chromeno[4,3-b][1,4]oxazines. Antiproliferative activity of the condensed heterocycles and precursors was evaluated against A2780 and WM35 cancer cell lines. For a 3-(N-chloroacetylamino)-flavan-4-ol derivative, showing structural analogy with acyclic acid ceramidase inhibitors, 0.15 μM, 3.50 μM, and 6.06 μM IC50 values were measured against A2780, WM35, and HaCat cell lines, and apoptotic mechanism was confirmed. Low micromolar IC50 values down to 2.14 μM were identified for the thiazole- and pyrrole-condensed 2H-chromene derivatives. Enantiomers of the condensed heterocycles were separated by HPLC using chiral stationary phase, HPLC-ECD spectra were recorded and TDDFT-ECD calculations were performed to determine the absolute configuration and solution conformation. Characteristic ECD transitions of the separated enantiomers were correlated with the absolute configuration and effect of substitution pattern on the HPLC elution order was determined.

Substituent Interactions in Di- and Tri-acyl Derivatives of cis- and trans- 2-Hydrazinocyclopentanol

1973 ◽  
Vol 51 (10) ◽  
pp. 1587-1597 ◽  
Author(s):  
J. A. Campbell ◽  
Donald Mackay
Keyword(s):  
Acetyl Derivative ◽  
Ester Group ◽  
Major Product ◽  
Amide Group ◽  
Acid Mixture ◽  
Tosyl Chloride ◽  
Cis And Trans ◽  
Work Up ◽  
Derivatives Of ◽  
Acyl Derivatives

The action of thionyl chloride followed by an alkaline work-up quantitatively isomerizes trans-1,2-dibenzoyl-1-(2-hydroxylcyclopentyl)hydrazine(5) to cis-2-benzoyl-1-(2-benzoyloxycyclopentyl)hydrazine (3). One equivalent of tosyl chloride in pyridine converts 5 to an intermediate which can be hydrolyzed to a mixture of 3 and 5 or can be transformed to the N-tosyl derivative 13 by tosylation and then hydrolysis. Oxazolidine structures are suggested as intermediates for these reactions.The alcohol 2 can also be isomerized to 3, using 0.8 N aqueous ethanolic hydrochloric acid, to which 5 is inert. The ester 3 is again the major product in the hydrolysis by this acid mixture of the cis-tribenzoyl derivative 17, the cis-N1-p-anisoyl derivative 21a and the cis-N1-acetyl derivative 21b, the amide group being cleaved much more rapidly than the ester, especially in the case of 21b. A mechanism involving ester participation by way of an oxazolidinium cation is proposed for these amide hydrolyses, and this is supported by tracer studies.The trans-esters 24a and b hydrolyze mainly at the ester group with retention of configuration.Polymorphism is a common phenomenon among the title compounds.

13C magnetic resonance studies. 144. An examination of β-enolization in the bicyclo[3.3.1]- and [3.2.2]nonan-2-one system

1993 ◽  
Vol 71 (8) ◽  
pp. 1099-1105 ◽  
Author(s):  
David J. Muir ◽  
J.B. Stothers
Keyword(s):  
Electron Transfer ◽  
Magnetic Resonance ◽  
Major Product ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Magnetic Resonance Studies ◽  
Unsaturated Ketones ◽  
A Minor ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

While 3,3-dimethylbicyclo[3.3.1]nonan-2-one (5) is stable under strongly basic conditions (t-BuO−/t-BuOH/185 °C), its isomer, 3,3-dimethylbicyclo[3.2.2]nonan-2-one (6), is slowly transformed to 5. Similarly, 3,3-dimethylbicyclo-[3.2.2]non-6-en-2-one (8b) rearranges to a [3.3.1] isomer but the latter is not stable. Experiments with 3,3-dimethylbicyclo[3.3.1]non-6-en-2-one (7) revealed that it is converted to five compounds, none of which is 8b. The major product, 8,8-dimethylbicyclo[4.3.0]non-1(6),-en-7-one (11) arises from β-enolate rearrangement. Enone 11 undergoes slow reduction to cis- and trans-8,8-dimethylbicyclo[4.3.0]nonan-7-one, presumably by single electron transfer. Experiments with 11 alone showed that β-enolate rearrangement of 7 → 11 is unidirectional. Haller–Bauer cleavage to acidic products occurs as a minor process in the reactions of the unsaturated ketones. The structures of the products were established primarily from their 1H and 13C magnetic resonance spectra.

Synthesis and thermolysis rate constants of diastereomeric oxadiazoline sources of acetoxy(methoxy)carbene — Reaction of acetoxy(methoxy)carbene with isocyanates

2006 ◽  
Vol 84 (7) ◽  
pp. 927-933 ◽  
Author(s):  
Wojciech Sokol ◽  
John Warkentin
Keyword(s):  
Acetic Acid ◽  
Ethyl Acetate ◽  
Carbonyl Group ◽  
Rate Constants ◽  
Acid Catalysis ◽  
Major Product ◽  
Acetyl Group ◽  
Methyl Pyruvate ◽  
Acetyl Transfer ◽  
Cis And Trans

Oxidation of the methoxycarbonylhydrazone of p-methoxyacetophenone affords both the cis- and trans-2-acetoxy-2-methoxy-5-(p-methoxyphenyl)-5-methyl-Δ3-1,3,4-oxadiazolines (also known as corresponding 2,5-dihydro-1,3,4-oxadiazoles) as well as methyl 1-acetoxy-1-(p-methoxyphenylethyl)diazenecarboxylate. The three isomers were separated and identified by spectroscopic means. Methyl 1-acetoxy-1-(p-methoxyphenylethyl)diazenecarboxylate is the major product from oxidation in dichloromethane. Oxidation in acetic acid did not afford the oxadiazolines but gave the diazenecarboxylate and, in addition, 1-(p-methoxyphenyl)ethyl acetate. Attempts to isomerize the diazenecar boxylate to the oxadiazolines by acid catalysis were not successful. Thermolysis of the oxadiazolines at 50.4 °C occurred with approximately the same rate constant (ca. 3.6 × 10–5 s–1) to afford acetoxy(methoxy)carbene, which rearranges to methyl pyruvate by acetyl transfer. The carbene, which reacts with relatively unhindered isocyanates to transfer the methoxy carbonyl group to carbon and the acetyl group to nitrogen, can be considered an acyl anion equivalent in that reaction.Key words: acetoxy(methoxy)carbene, diazene, oxadiazoline, isocyanate, (acetylamino)oxoacetate.

scholarly journals Twofold C-H Activation-Based Enantio- and Diastereoselective C-H Arylation Using Diarylacetylenes as Rare Arylating Reagents

2021 ◽  
Author(s):  
Panjie Hu ◽  
Lingheng Kong ◽  
Fen Wang ◽  
Xiaolin Zhu ◽  
Xingwei Li
Keyword(s):  
Bond Activation ◽  
Major Product ◽  
Activation Reaction ◽  
Axial Chirality ◽  
Mild Conditions ◽  
Straightforward Method ◽  
Axially Chiral

<p>C-H bond activation has been established as an attractive strategy to access axially chiral biaryls, and the most straightforward method is direct C-H arylation of arenes. However, the arylating source has been limited to several classes of reactive and bulky reagents. Reported herein is rhodium-catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes for enantio- and diastereoselective construction of biaryls with both central and axial chirality. This twofold C-H activation reaction stays contrast to the previously explored Miura-Satoh type 1:2 coupling of arenes and alkynes in terms of chemoselectivity and proceeded under mild conditions with the alkyne acting as a rare arylating reagent. Both C-H activation events are stereo-determining and are under catalyst control, with the 2<sup>nd</sup> C-H activation being diastereo-determining in a remote fashion. Analysis of the stereochemistries of the major and side products suggests moderated enantioselectivity of the initial C-H activation-desymmetrization process. However, the minor stereoisomeric (<i>R</i>) intermediate is consumed more readily in undesired protonolysis, eventually resulting in high enantio- and diastereoselectivity of the major product.</p>

Total synthesis of ylango sesquiterpenoids: (+)-cis- and (+)-trans-sativenediol, (+)-helminthosporal, (+)-helminthosporol, prehelminthosporal, prehelminthosporal diethyl acetal, (+)-victoxinine, (+)-isosativenediol

1977 ◽  
Vol 55 (6) ◽  
pp. 1039-1044 ◽  
Author(s):  
Edward Piers ◽  
Hans-Peter Isenring
Keyword(s):  
Total Synthesis ◽  
Trifluoroacetic Acid ◽  
Chromium Trioxide ◽  
Major Product ◽  
Hydroxy Ketone ◽  
Diethyl Acetal ◽  
Total Syntheses ◽  
Tricyclic Ketone ◽  
Cis And Trans ◽  
Synthetic Transformations

Oxidation of the previously prepared olefinic alcohol 26 with chromium trioxide – pyridine in dichloromethane containing trifluoroacetic acid gave the tricyclic ketone 29 as the major product. Hydroxylation of the latter, followed by reduction of the resulting α-hydroxy ketone 31, afforded a 1:1 mixture of (+)-cis- (22) and (+)-trans-sativenediol (23). In view of earlier synthetic transformations reported by a number of different researchers, the present work also constitutes formal total syntheses of the enantiomers of the following sesquiterpenoids: (−)-helminthosporal (1), (−)-helminthosporol (2), prehelminthosporal (3), prehelminthosporal diethyl acetal (4), (−)-victoxinine (8), and (−)-isosativenediol (19).

scholarly journals Nucleophilic Substitution at Tetracoordinate Phosphorus.Stereochemical Course and Mechanisms of Nucleophilic Displacement Reactions at Phosphorus in Diastereomeric cis- and trans-2-Halogeno-4-methyl-1,3,2-dioxaphosphorinan-2-thiones: Experimental and DFT Studies

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3655
Author(s):  
Marian Mikołajczyk ◽  
Barbara Ziemnicka ◽  
Jan Krzywański ◽  
Marek Cypryk ◽  
Bartłomiej Gostyński
Keyword(s):  
Dft Calculations ◽  
Alkaline Hydrolysis ◽  
Density Functional ◽  
Phosphorus Pentachloride ◽  
Major Product ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Displacement Reactions ◽  
Single Transition ◽  
Cis And Trans

Geometrical cis- and trans- isomers of 2-chloro-, 2-bromo- and 2-fluoro-4-methyl-1,3,2-dioxaphosphorinan-2-thiones were obtained in a diastereoselective way by (a) sulfurization of corresponding cyclic PIII-halogenides, (b) reaction of cyclic phosphorothioic acids with phosphorus pentachloride and (c) halogen–halogen exchange at PIV-halogenide. Their conformation and configuration at the C4-ring carbon and phosphorus stereocentres were studied by NMR (1H, 31P) methods, X-ray analysis and density functional (DFT) calculations. The stereochemistry of displacement reactions (alkaline hydrolysis, methanolysis, aminolysis) at phosphorus and its mechanism were shown to depend on the nature of halogen. Cyclic cis- and trans-isomers of chlorides and bromides react with nucleophiles (HO−, CH3O−, Me2NH) with inversion of configuration at phosphorus. DFT calculations provided evidence that alkaline hydrolysis of cyclic thiophosphoryl chlorides proceeds according to the SN2-P mechanism with a single transition state according to the potential energy surface (PES) observed. The alkaline hydrolysis reaction of cis- and trans-fluorides afforded the same mixture of the corresponding cyclic thiophosphoric acids with the thermodynamically more stable major product. Similar DFT calculations revealed that substitution at phosphorus in fluorides proceeds stepwise according to the A–E mechanism with formation of a pentacoordinate intermediate since a PES with two transition states was observed.

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