THE CONDENSATION OF CERTAIN γ-KETONIC ESTERS WITH AROMATIC ALDEHYDES

1932 ◽  
Vol 6 (6) ◽  
pp. 605-613 ◽  
Author(s):  
C. F. H. Allen ◽  
G. F. Frame
Keyword(s):  
Carbonyl Group ◽  
Aromatic Aldehydes ◽  
Sodium Methylate ◽  
Ring Closure ◽  
Aryl Group ◽  
Appropriate Treatment ◽  
Ketone Carbonyl ◽  
Branched Chain ◽  
Cyclic Compounds ◽  
Chloride Methyl

The condensation of methyl and ethyl α-phenyl-β-(para-substituted)benzoyl propionates with benzaldehyde and piperonal in the presence of sodium methylate, followed by acidification, has been found to produce cyclic compounds; the latter are shown to be lactols, six of which are described. The spontaneous ring closure is probably due to the highly branched chain. A mechanism for the reaction is proposed.On oxidation with chromic acid, α-diketones are formed; the latter contain the aryl group introduced as aldehyde. The lactols resemble triphenylcarbinol in several respects, forming a chloride, methyl ether, and acetate on appropriate treatment, all of which, on hydrolysis, regenerate the lactol. They also give colored solutions with concentrated sulphuric acid, from which the starting material is recovered on addition to water. From this work it is evident that in arylated γ-ketonic esters the hydrogen atom alpha to the ketone carbonyl group is more active in alkaline aldol condensations than the hydrogen in the alpha position to the carbalkoxy carbonyl group; the observation of others, that the conjugated system [Formula: see text] is more stable than [Formula: see text], has been confirmed.

CYCLIC COMPOUNDS CONTAINING A CARBONYL GROUP; A MECHANISM FOR THE FORMATION OF PYRYLLIUM SALTS FROM 1,5-DIKETONES

1933 ◽  
Vol 9 (6) ◽  
pp. 574-582 ◽  
Author(s):  
C. F. H. Allen ◽  
H. R. Sallans
Keyword(s):  
Carbonyl Group ◽  
Methyl Ether ◽  
Ring Closure ◽  
Closed Ring ◽  
Second Mode ◽  
Ring Structures ◽  
Group A ◽  
Plausible Mechanism ◽  
Cyclic Compounds

In the presence of alkali, cyclohexanone and its homologues add to chalcones to form either semicyclic diketones or dicyclic keto-alcohols; the latter contain a carbonyl bridge, and the former can be converted into closed ring structures and dehydrated to form substances having a carbonyl bridge. In these dicyclic ketones the bridge is not removed by heating, in contrast to the behavior of certain other compounds having a similar ring system.A second mode of ring closure gives rise to pyryllium salts; the isolation of a methyl ether has made it possible to devise a plausible mechanism for this hitherto obscure reaction. Four varieties of salts are described, the perchlorates being obtained by a different procedure than that previously employed.

Photochemical behaviour of α-diketones on a silica gel surface: a novel photoreaction by intramolecular trapping of an excited ketone carbonyl oxygen by an aryl group

1997 ◽  
pp. 1271-1274 ◽  
Author(s):  
Tadashi Hasegawa ◽  
Manabu Imada ◽  
Yoshihiro Imase ◽  
Yuko Yamazaki ◽  
Michikazu Yoshioka
Keyword(s):  
Silica Gel ◽  
Carbonyl Oxygen ◽  
Aryl Group ◽  
Ketone Carbonyl ◽  
Photochemical Behaviour

A novel method for the geminal dialkylation of the carbonyl group of aromatic aldehydes and ketones

1986 ◽  
Vol 27 (15) ◽  
pp. 1719-1722 ◽  
Author(s):  
M. Clarembeau ◽  
A. Krief
Keyword(s):  
Carbonyl Group ◽  
Aromatic Aldehydes ◽  
Aldehydes And Ketones ◽  
Novel Method

Silaheterocyclen, VII. Reaktionen des Dichlorneopentylsilaethens mit Aldehyden / Silaheterocycles, VII. Reactions of Dichloroneopentylsilene with Aldehydes

1990 ◽  
Vol 45 (6) ◽  
pp. 909-920 ◽  
Author(s):  
Norbert Auner ◽  
Claudia Seidenschwarz
Keyword(s):  
Carbonyl Group ◽  
Aromatic Aldehydes ◽  
Product Formation ◽  
Membered Ring ◽  
Coupling Reactions ◽  
Zwitterionic Intermediate

Dichloroneopentylsilene, Cl2Si=CHCH2Bu' (1), is produced from vinyltrichlorosilane (2) and LiBu' in n-pentane at —78 °C. The reactions of 1 with aromatic aldehydes like benzaldehyde and the 4-methoxy- or 4-fluoro-substituted derivatives, naphthalene-1- and -2- and 9-anthracenecarbaldehyde, furfurale and its S-analogous thiophene carbaldehyde yield 1,2-silaoxetanes by [2+2] cycloaddition with the carbonyl group. The same is true for the reactions of 1 with pivaline-, butyr- and acetaldehyde. The silaoxetanes cannot be isolated; the formation of dichlorovinylsiloxanes and the olefinic compounds R—CH=CH —CH2Bu′suggests that the cycloreversion of the Si—O four-membered ring competes with an intramolecular isomerization, evidently via formation of a zwitterionic intermediate . The product formation by coupling reactions of lithiated aldehydes and 2 is excluded by performing analogous reactions with the chlorosilanes Me2SiCl(R) (R = Cl, Me, Vi).

Epoxide of a ketene acetal. The first 2,2-dialkoxyoxirane to be isolated

2001 ◽  
Vol 79 (2) ◽  
pp. 110-113 ◽  
Author(s):  
Malgorzata Dawid ◽  
Paul C Venneri ◽  
John Warkentin
Keyword(s):  
Ir Spectroscopy ◽  
Carbonyl Group ◽  
Ring Closure ◽  
Nucleophilic Attack ◽  
Carbonyl Carbon ◽  
Subsequent Formation ◽  
H Nmr ◽  
Carbonyl Ylide ◽  
Ketene Acetal ◽  
C Nmr

Dimethoxycarbene, generated at 110°C in benzene by thermolysis of 2,2-dimethoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazoline, reacted with cyclohexanone to afford 2,2-dimethoxyspiro[2.5]-1-oxaoctane. It is the first oxirane of a ketene acetal that could be isolated and characterized by 1H NMR-, 13C NMR-, and IR spectroscopy. The identical oxirane might be expected from conrotatory cyclization of the appropriate carbonyl ylide. That ylide was generated under identical conditions by thermolysis of an oxadiazoline precursor (3,4-diaza-2,2-dimethoxy-1-oxaspiro[4.5]dec-3-ene) (14). The ylide could either cyclize or fragment to dimethoxycarbene and cyclohexanone. Addition of 4-tert-butylcyclohexanone, to trap dimethoxycarbene in competition with the cyclohexanone generated from 14 and, to leave the ylide closure pathway as the only route to the oxirane, showed that the carbonyl ylide does cyclize. However, fragmentation of the carbonyl ylide is relatively fast compared to its cyclization and most of it fragments to dimethoxycarbene and cyclohexanone. Oxirane formation from the carbene and ketone is probably either a concerted cycloaddition or it occurs in two steps, by nucleophilic attack at the carbonyl carbon to form the C—C bond first, prior to ring closure. If the carbene is bonded first to O of the carbonyl group, as it is in the carbonyl ylide, subsequent formation of the C—C bond is too slow, relative to fragmentation of the ylide, to afford the oxirane ring efficiently.Key words: carbonyl ylide, dialkoxyoxirane, dimethoxycarbene, oxadiazoline, oxirane.

Stereocontrolled catalytic hydrogenations of 3-oxocholestanes and some related compounds to the corresponding axial 3-alcohols

1980 ◽  
Vol 58 (11) ◽  
pp. 1061-1068 ◽  
Author(s):  
Masayoshi Ishige ◽  
Michio Shiota
Keyword(s):  
Carbonyl Group ◽  
Cobalt Catalyst ◽  
Solvent Polarity ◽  
The Other ◽  
Nonpolar Solvents ◽  
Ketone Carbonyl Group ◽  
Other Hand ◽  
Ketone Carbonyl ◽  
Related Compounds ◽  
Alcohol Formation

Catalytic hydrogenations of 5α-cholestan-3-ones and related compounds with Urushibara nickel A catalyst in cyclohexane gave a distinct preponderance of unstable axial 3α-ols. Product ratios of axial alcohols decreased with increasing solvent polarity. For 3-oxo-5α-steroids, the cobalt catalyst was less selective for the axial alcohol formation. On the other hand, conversion of 5β-cholestan-3-one into the corresponding axial 3β-ol was most successfully attained by hydrogenation catalyzed by Urushibara cobalt A catalyst in methanol. For such a 5β-ketone, alcoholic media with higher polarities were more favorable for giving the product rich in axial alcohol. The stereochemistry of the products obtained from hydrogenations conducted in nonpolar solvents may be understood in terms of the steric congestion around the ketone carbonyl group. However, when alcohols were used as solvents, the product ratios obtained did not correlate well with the congestion ratios of substrates.

THE CONDENSATION OF CERTAIN γ-KETONIC ESTERS WITH AROMATIC ALDEHYDES. II

1933 ◽  
Vol 8 (2) ◽  
pp. 137-141 ◽  
Author(s):  
C. F. H. Allen ◽  
G. F. Frame ◽  
J. B. Normington ◽  
C. V. Wilson
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Chloride ◽  
Aromatic Aldehydes ◽  
Sodium Methylate ◽  
Independent Method ◽  
Unsaturated Ketones ◽  
Similar Work ◽  
Substituent Group ◽  
Benzoyl Radical

The condensation of benzaldehyde with methyl and ethyl α-aryl-β-benzoyl propionates in the presence of sodium methylate, followed by acidification, gave unsaturated ketonic acids. This result was unexpected in view of the previously described similar work in which lactols were formed; the only difference in the molecules is the absence of a substituent group in the benzoyl radical of the ester.The structure of the acids was carefully determined. On being heated they lost carbon dioxide, forming α, β-unsaturated ketones. One of the latter added hydrogen chloride to give two stereoisomeric saturated chloroketones, which were also synthesized by an independent method.

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