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Dehydrogenation of ketones

Bohlmann (207) reported the reaction of /I -dehydroquinolizidine with methyl vinyl ketone and with propargyl aldehyde forming a partially saturated derivative of julolidine 135 and julolidine (136), respectively. Compound 135 can be prepared also by mercuric acetate dehydrogenation of ketone 137, which is formed by condensation of 1-bromoethylquinolizi-dine with ethyl acetoacetate (Scheme 11). [Pg.283]

Dehydrogenation of ketones with methyl 2-pyridinesuIfinate Ketone Product Yield (%)... [Pg.34]

Davy reagents 32,38 decarboxylation 64,67 Dehydrogenation of ketones 55 Dehydrohalogenation 57 Deracemization 68 Desulfurization 75 of dithioacetals 78,100 of dithioesters 69... [Pg.107]

Attempts to dehydrogenate ketones have been plagued by product inhibition, particularly by cyclometallation of the initially produced a,/3-unsaturated ketones or by additions of aromatized cyclic ketones. Within the range of substrates that is presently very limited by these factors, however, regioselective dehydrogenation of ketones has been successfully achieved [31]. [Pg.621]

Side Note 12.4. Dehydrogenation of Ketones via Silyl Enol Ethers... [Pg.513]

Matsuo and Aizawa71 have recently reported a new tandem reaction based on the dehydrogenation of ketones to the corresponding a,/3-unsaturated ketones, 77. They employed... [Pg.79]

Table 4 Dehydrogenation of Ketone, Ester, Lactone and Lactam Enolates ... Table 4 Dehydrogenation of Ketone, Ester, Lactone and Lactam Enolates ...
Copper(II) bromide is another reagent that has been used successfully for the dehydrogenation of ketones and amides (equation 21). This procedure, which presumably proceeds via the a-bromo compounds, (c/. Section 2.2.2) was found to have particular advantages over a number of alternative methods for the dehydrogenation of some dihydrouracils. ... [Pg.144]

New applications of dichlorodicyanobenzoquinone (DDQ) for the dehydrogenation of ketones include the conversion of a 4,7-dien-3-one into the 4,6,8(14)-trienone, which is further dehydrogenated to the l,4,6,8(14)-tetraenone with acidic catalysis.The dehydrogenation of a 4-en-6-one with DDQ affords the 2,4-dien-6-one. Selective 1,2-dehydrogenation of 5a-cholestan-3-one has been achieved with palladium acetylacetonate and oxygen.Possible alternative mechanisms are discussed. [Pg.273]

Bierling, B., Kirschke, K., Oberender, H., Schulz, M. Dehydrogenation of ketones with palladium(ll) compounds. J. Prakt. Chem. 1972, 314, 170-180. [Pg.667]

Reactions Involving Enols or Enolic Derivatives.—The full account was reported for the dehydrogenation of ketones using benzene seleninic anhydride.77 Further studies were reported on catalysts specific for the isomerization of A5-cholestenone to A4-cholestenone.78... [Pg.299]

Hydroxybenzo[b]thiophene is conveniently obtained by the dehydrogenation of ketone 68.292 4-, 5-, and 6-Methoxy-3-methylbenzo[f>]thiophene-2-carboxylic acids are obtained from the appropriate j3-aryl-a-mercaptoacrylic acid (Ref. 2, p. 233) by cyclization with chlorine477 the reaction is cleaner than with iodine, but some ring chlorination may also occur.247 The methoxy... [Pg.230]

Conjugated ketones. Dehydrogenation of ketones via their lithium enolates on treatment with f-BuN=S(Cl)Ph at —78° is very convenient. [Pg.85]

Dehydrogenation of ketones. This reagent is an attractive alternative, particularly to selenium dioxide, for dehydrogenation of ketosteroids. The by-product is diphenyl diselenide, which is easily removed and reoxidized to the anhydride. Moreover, the anhydride is fairly inert to double bonds. [Pg.325]

Dehydrogenation. Recent syntheses of eight isomeric hydroxybenzo[a]pyrenes involved dehydrogenation of ketones to phenols (for example, equation I) as the final step. Pd black (Engelhard) was found to be generally superior to sulfur for this reaction, which was carried out at near reflux in high-quality 1-methyl-naphthalene under argon. The choice of solvent is critical. ... [Pg.141]


See other pages where Dehydrogenation of ketones is mentioned: [Pg.385]    [Pg.247]    [Pg.306]    [Pg.495]    [Pg.32]    [Pg.85]    [Pg.162]    [Pg.395]    [Pg.385]    [Pg.201]    [Pg.135]    [Pg.137]    [Pg.144]    [Pg.135]    [Pg.137]    [Pg.144]    [Pg.100]    [Pg.227]    [Pg.249]    [Pg.32]    [Pg.62]    [Pg.241]    [Pg.213]    [Pg.135]    [Pg.137]    [Pg.144]   
See also in sourсe #XX -- [ Pg.299 ]

See also in sourсe #XX -- [ Pg.188 , Pg.189 , Pg.190 , Pg.191 , Pg.442 ]




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Dehydrogenation of Butan-2-ol to Methyl Ethyl Ketone

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