Phosphonium salts. III. The action of cyanide ion and other nucleophiles on some bis-phosphonium salts

1969 ◽  
Vol 22 (7) ◽  
pp. 1405 ◽  
Author(s):  
JJ Brophy ◽  
MJ Gallagher
Keyword(s):  
Sodium Azide ◽  
Sodium Methoxide ◽  
Sodium Acetate ◽  
Potassium Cyanide ◽  
Dimethyl Sulphoxide ◽  
High Yield ◽  
Phosphonium Salts ◽  
Elimination Reaction ◽  
Cyanide Ion ◽  
Reaction Proceeds

Cyclic and acyclic bis-phosphonium salts with a two-carbon bridge are smoothly cleaved to phosphines in high yield by potassium cyanide in dimethyl sulphoxide. Evidence is presented that the reaction proceeds by an elimination-addition sequence. An elimination reaction also occurs when sodium methoxide, sodium azide, sodium acetate, and triethylamine react with ethane-1,2-bis(tri-phenylphosphonium) dibromide. ��� In a novel reaction, triphenylphosphine is converted into its oxide by a mixture of sodium azide and dimethyl sulphoxide.

Diels–Alder adducts of 2-acetoxyfuran as a route to 2,3-functionalized 4-hydroxycyclohexanones. Application of X-ray diffraction to the problem of regio- and stereochemistry

1981 ◽  
Vol 59 (20) ◽  
pp. 2997-3006 ◽  
Author(s):  
D. Gravel ◽  
R. Deziel ◽  
F. Brisse ◽  
L. Hechler
Keyword(s):  
Maleic Anhydride ◽  
Sodium Methoxide ◽  
Diels Alder ◽  
Quantitative Yield ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Efficient Access ◽  
Reaction Proceeds ◽  
Cyclopropane Derivatives

The Diels–Alder adducts of 2-acetoxyfuran and maleic anhydride and 2-acetoxyfuran and chloromethylmaleic anhydride have been obtained and their dihydro derivatives manipulated in high yield to various 2,3-functionalized 4-hydroxycyclohexanones. In all cases the hemiketal acetate bridge of the oxabicyclo[2.2.1] derivatives was cleaved smoothly using sodium methoxide in methanol at 0 °C; however, in the case of the chloromethyl compounds the reaction proceeds further to give an almost quantitative yield of the corresponding fused cyclopropane derivatives. These sequences, starting from the readily accessible but seldom used 2-acetoxyfuran, are therefore extremely advantageous to gain rapid and efficient access to a number of 2,3-functionalized 4-hydroxycyclohexanones. In the case of the adduct involving chloromethylmaleic anhydride, stereochemistry and regiochemistry were established by X-ray diffraction on the dihydro derivative.

Highly Diastereoselective and Irreversible Aldol Reactions of N-Sulfonylimidates

Synthesis ◽  
2016 ◽  
Vol 48 (19) ◽  
pp. 3413-3419 ◽  
Author(s):  
Hannah Bartrum ◽  
Sébastien Carret ◽  
Jean-François Poisson
Keyword(s):  
Lewis Acid ◽  
High Yield ◽  
Aldol Reactions ◽  
Titanium Complex ◽  
Reaction Proceeds

A mild method for the aldolization of N-sulfonylimidates was developed. The reaction proceeds in excellent diastereoselectivity to provide a range of useful β-hydroxyimidates in high yield. The innate reversibility of the reaction is suppressed by the use of a titanium complex as a Lewis acid.

Acridone studies. X. Reactions of the isomeric Bromo-10-methylacridones with sodium methoxide in methanol and in dimethyl sulphoxide

1972 ◽  
Vol 25 (3) ◽  
pp. 585 ◽  
Author(s):  
DKC Hodgeman ◽  
RH Prager
Keyword(s):  
Sodium Methoxide ◽  
Dimethyl Sulphoxide ◽  
Radical Chain

The isomeric 1-, 2-, 3-, and 4-bromo-10-methylacridones undergo a radical chain reduction to 10-methylacridone in the presence of sodium methoxide in methanol. Evidence for the mechanism is presented. In the presence of methanol-free dimethyl sulphoxide, the 1- and 3-bromo-10-methylacridones are cleanly converted by sodium methoxide into the respective methoxy compounds, and the rates have been measured at 40�. In the same solvent, the 2- and 4-bromo isomers are again reduced by sodium methoxide.

scholarly journals The counteracting effect of potassium cyanide in sodium azide-inhibited germination of Paulownia tomentosa  Steud. seeds

2005 ◽  
Vol 57 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Suzana Zivkovic ◽  
Dragoljub Grubisic ◽  
Zlatko Giba ◽  
Radomir Konjevic
Keyword(s):  
Seed Germination ◽  
Light Pulse ◽  
Sodium Azide ◽  
Incubation Medium ◽  
Red Light ◽  
Potassium Cyanide ◽  
Inhibitory Effect ◽  
Escape Time ◽  
Paulownia Tomentosa ◽  
Respiratory Inhibitors

The effect of some respiratory inhibitors on light-induced Paulownia tomentosa Steud. seed germination was studied. Millimolar solution of sodium azide was sufficient to completely prevent germination induced by a 5-min red light pulse. The inhibitory effect of azide was absent if seeds were rinsed before phytochrome activation by light. Sodium azide was effective only if present in the period of Pfr activity. The escape time from azide inhibition compared to the escape from far-red light action, was delayed for about 24 hours. When azide was applied after phytochrome activation, its effect depended on how long it was present in the incubation medium. The removal of azide allowed full restoration of germination by another red light pulse and the far-red escape time did not differ from the escape of untreated, i.e. water-imbibed seeds. Potassium cyanide alone did not produce any effect in light-stimulated germination of these seeds. However, it counteracted the inhibitory effect of azide in light-stimulated germination, if applied simultaneously at a concentration three times higher.

An ionic chain mechanism for the substitution of an acetate group by the 2-Nitropropan-2-ide ion in benzylidene diacetates

1976 ◽  
Vol 29 (2) ◽  
pp. 327 ◽  
Author(s):  
DJ Freeman ◽  
PJ Newcombe ◽  
RK Norris
Keyword(s):  
Good Yield ◽  
Dimethyl Sulphoxide ◽  
Acetate Group ◽  
Chain Mechanism ◽  
Elimination Reaction ◽  
Nucleophilic Cleavage ◽  
Enol Acetates ◽  
Subsequent Elimination

The reaction of 16 arylmethylene diacetates [benzylidene diacetates; ArCH(OAc)2] with lithium 2-nitropropan-2-ide in dimethyl sulphoxide has been studied. With the exception of aryl rings bearing strongly electron-donating substituents a ready reaction takes place giving l-aryl-2-methyl-2-nitropropyl acetates in good yield. The mechanism of this reaction, in which an acetate group is formally substituted by a (CH3)2C(N02) group, has been shown to be an ionic chain mechanisminvolving nucleophilic cleavage of the diacetate to catalytic quantities of the corresponding arene carbaldehyde (ArCHO) which subsequently undergoes a Henry condensation followed by a transacetylation reaction. In some cases (nitro heteroaromatic derivatives) a subsequent elimination reaction gives enol-acetates [ArC(OAc)=C(CH3)2].

scholarly journals EXPERIMENTALLY INDUCED CHROMOSOME ABERRATIONS IN PLANTS

1957 ◽  
Vol 3 (3) ◽  
pp. 363-380 ◽  
Author(s):  
B. A. Kihlman
Keyword(s):  
Hydrogen Peroxide ◽  
Heavy Metal ◽  
Sodium Fluoride ◽  
Sodium Azide ◽  
Chromosome Aberrations ◽  
Alternative Hypothesis ◽  
Potassium Cyanide ◽  
Complexing Agents ◽  
Butyl Hydroperoxide ◽  
Metal Complexing Agents

The finding of Lilly and Thoday that potassium cyanide produces structural chromosome changes in root tips of Vicia faba was confirmed. Like mustards, diepoxides, and maleic hydrazide, potassium cyanide seems to act on cells at early interphase. A tendency of cyanide breaks to be concentrated in heterochromatic segments of the chromosomes was evident. The production of chromosome aberrations by cyanide proved to be practically unaffected by the temperature during treatment. In agreement with Lilly and Thoday, the effect of potassium cyanide was found to be dependent on oxygen tension during treatment. The effect of potassium cyanide increases with increasing oxygen concentration up to 100 per cent oxygen. In the absence of oxygen, potassium cyanide was not completely inactive, but produced a low, though significant frequency of aberrations. Pretreatments with 2.4-dinitrophenol did not influence the effect of potassium cyanide. When bean roots were treated with potassium cyanide before a treatment with 8-ethoxycaffeine, or at the same time as they were treated with 8-ethoxycaffeine, the effect of 8-ethoxycaffeine was almost completely suppressed. The effects of a number of other heavy metal complexing agents were also tested. Sodium fluoride, potassium thiocyanate, carbon monoxide, o-phenanthroline, 2.2-bipyridine, and sodium azide were without radiomimetic effect under the conditions employed, and so was a mixture of sodium azide and sodium fluoride. A low, but quite significant, radiomimetic effect was obtained after treatments with sodium diethyldithiocarbamate, cupferron, and 8-hydroxyquinoline. Under anaerobic conditions, the effects of cyanide and cupferron were both quantitatively and qualitatively indistinguishable. Unlike the effect of cyanide, the effect of cupferron was not enhanced by the presence of oxygen. The effects of the same heavy metal complexing agents were tested on the activities of the enzymes catalase and peroxidase. The activities of both of these enzymes were found to be totally inhibited only by potassium cyanide. In the other cases, little correlation was found between ability to inhibit the activities of these enzymes and ability to produce chromosome aberrations. In a number of experiments, hydrogen peroxide was found to be without radiomimetic effect, whether alone or in combination with potassium cyanide. t-Butyl hydroperoxide proved to be active. The effect of t-butyl hydroperoxide was substantially increased by pretreatments with 2.4.-dinitrophenol. The results are discussed, and it is concluded that the observations made do not support the hypothesis that hydrogen peroxide is involved in the production of chromosome aberrations by potassium cyanide. The possibility that organic peroxides are involved cannot be excluded on the bases of the experimental results. As an alternative hypothesis, it is suggested that iron or other heavy metals are present in the chromosomes and that cyanide and other heavy metal complexing agents produce chromosome aberrations by reacting with these metals.

4,5-Seco-4,6-cyclosteroids. III. Observations on the course of reductive rearrangement of 6β-Bromo-4β,5-epoxy-5β-cholestan-3β-ol

1969 ◽  
Vol 22 (4) ◽  
pp. 807 ◽  
Author(s):  
DJ Collins ◽  
JJ Hobbs ◽  
RJ Rawson
Keyword(s):  
Hydrogen Bromide ◽  
High Yield ◽  
Lithium Aluminium Hydride ◽  
Experimental Conditions ◽  
Lithium Aluminium ◽  
Reaction Proceeds ◽  
Derivatives Of

It has been shown that reductive rearrangement of 6β-bromo-4β,5-epoxy- 5β-cholestan-3β-ol (I) to 4,5-seco-4,6-cycle-6β-cholestane-3β,5α-diol (IXa) with lithium aluminium hydride in tetrahydrofuran proceeds via 6β-bromo-5β-cholestane-3β,5-diol (IIa). Relevant reactions of the latter and the corresponding 3-ketone are discussed. ��� Similar conversion of the 3-epimer of (I) into 4,5-seco-4,6-cyclo- 6β-cholestane-3α,5α-diol (XIIIa) in high yield indicates that reductive rearrangement of the 6β-bromo-5β-hydroxy moiety proceeds without participation of the 3-aluminate complex. Some derivatives of (XIIIa) are described. ��� Experimental conditions required for the conversion of (I) into (IXa) are defined. ��� Combined evidence indicates that the reaction proceeds in a concerted manner by essentially base-catalysed, 1,3-elimination of hydrogen bromide from diol (IIa) with 4,5-bond migration to give the formal intermediate 3β-hydroxy-4,5-seco-4,6-cyclo-6β-cholestan-5-one (VI), further reduced to (IXa).

Synthèse et réactivité des halogéno-2 sulfonyl-2 aziridines

1979 ◽  
Vol 57 (15) ◽  
pp. 1958-1966 ◽  
Author(s):  
Jean-Marc Gaillot ◽  
Yvonne Gelas-Mialhe ◽  
Roger Vessiere
Keyword(s):  
Acidic Medium ◽  
Sodium Methoxide ◽  
Sodium Ethoxide ◽  
Potassium Cyanide

Carbon tetrahalide reacts rapidly with 2-phenylsulfonyl aziridines in the presence of KOH, leading to 2-phenylsulfonyl 2-haloaziridines.Starting with 2-isopropylsulfonyl aziridines, a monochloro and a dichloroaziridine are produced; the Ramberg–Bäcklund reaction is not observed.These halo compounds decompose either thermally or in acidic medium leading to N-substituted α-haloacetamides and α-phenylsulfonylacetamides. 2-Phenylsulfonyl 2-haloaziridines are unreactive toward potassium cyanide or sodium thiophenoxide. Sodium methoxide, sodium ethoxide, or sodium thioethoxide reduce them to 2-phenylsulfonyl aziridines; the reaction depends upon the solvent.

scholarly journals Copper(I)-Catalyzed Boryl Substitution of Allyl Aminals: Selective Synthesis of Linear γ-Aminoallylboronates

Synthesis ◽  
2017 ◽  
Vol 49 (21) ◽  
pp. 4738-4744 ◽  
Author(s):  
Hajime Ito ◽  
Yuta Takenouchi
Keyword(s):  
Amino Alcohol ◽  
High Yield ◽  
Selective Synthesis ◽  
Novel Approach ◽  
Reaction Proceeds ◽  
High Stereoselectivity

A novel approach for the selective synthesis of α-substituted γ-aminoallylboronates through a copper(I)-catalyzed γ-boryl-substitution of allyl aminals is developed. The reaction proceeds with high yield (up to 88%) and good E/Z selectivity (up to >95:5). Subsequent aldehyde allylation using allylboronates affords (Z)-anti-1,2-amino alcohol derivatives with high stereoselectivity (up to 91% yield, and up to 17:83 E/Z).

Selective transformations of secologanin: dihydroxylation

1981 ◽  
Vol 59 (2) ◽  
pp. 210-214 ◽  
Author(s):  
John Richard Purdy ◽  
Raymond G. Hamilton ◽  
Lalarukh Akhter ◽  
Stewart McLean
Keyword(s):  
High Yield ◽  
Side Chain ◽  
Conformational Preference ◽  
Large Excess ◽  
Reaction Proceeds ◽  
Small Excess

Sweroside tetraacetate (2b) has been converted in high yield by osmylation to the epimeric glycols 3 and 4 (R = H) which have been separated. This reaction proceeds with high chemoselectivity for reaction at the vinyl side chain but with low stereoselectivity, leading to a small excess of the 3-R isomer. Secologanin derivatives appear to show a much lower chemoselectivity in this reaction, but the stereoselectivity is considerably higher, and opposite to that in the sweroside example. Conditions have been found for oxidizing the dimethylacetal 5b of secologanin tetraacetate in useful yields to the epimeric glycols 6 and 7 (R = H); in this reaction a large excess of the 3-S isomer is formed. The reasons for these differences in selectivity appear to be related to differences between the two series in conformational preference.

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