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Hydroxymethylene compounds acetals

Yield.—66% theoretical (10 gms.). Colourless crystals insoluble in water M.P. 61° gives a deep violet coloration with ferric chloride and a bluish-green crystalline precipitate of copper benzoyl acetone with alcoholic copper acetate. This shows the compound to be tautomeric, a little of the enol form being present at ordinary temperatures. The acidity of the hydroxyl group in the enol form is not so marked as it is in the case of the hydroxymethylene compounds nevertheless, the metallic salts of benzoyl acetone and such di-ketones are remarkably stable, and on account of their great crystallising power have been used for the determination of the valency and atomic weight of the rare elements. They are also of importance in the modern theory of co-ordination. (C., 1900,1., 588 B., 34, 2584.)... [Pg.98]

Sodium acetate Japp-Klingemann reaction with hydroxymethylene compounds Hydrazones from diazonium salts... [Pg.393]

Ethonam (99), an imidazole derivative with a very different substitution pattern, is also reported to possess antifungal activity. To prepare it, alkylation of aminotetralin 94 with methylchloro-acetate gives the glycine derivative 95. Heating with formic acid then affords the amide 96 this compound is then reacted with ethyl formate to yield hydroxymethylene ester 97. Reaction with isothio-cyanic acid gives the imidazole-2-thiol 98. (The... [Pg.249]

Several 21,22-seco-diacids (150) have been prepared in the 20/S,28-epoxy-18a,19/8H-ursane series by oxidation of the corresponding 22-hydroxymethylene-21-ketones (151). Reaction of the 21-ketone (152) with oxygen in an alkaline medium afforded the a-hydroxy-acid (153) and the seco-diacid (150). ° Several interesting reactions were observed during this work. ° While pyrolysis of the a-acetoxy-acid (154) yielded the ketone (155) pyrolysis of the seco-diacid anhydride resulted in loss of carbon monoxide and formation of the lactone (156). Lead tetra-acetate oxidation of the ketone (155) [or the hydroxy-acid (153)] followed a Baeyer-Villiger pathway to the lactone (156). The ketone (155) was very susceptible to reduction in the presence of alcoholic alkali. The mass spectral fragmentation of a series of compounds based on 20/8,28-epoxy-18a,19/8H-ursane has been examined. ... [Pg.149]

Having precursor 407 in hand. Brooks et al. were able to synthesize anguidine (376) in a further 17 steps. Thus, precursor 407 was converted into enamine 409, which was hydrolyzed to hydroxymethylene derivative 410. Michael reaction with butanone afforded the exo product 411. Followed by an intramolecular Michael aldol condensation, enone 412 was obtained, which was methylated to the allyl alcohol 413 using methyl iodide. Subsequent reduction with Ufliium aluminum hydride led to tetraol 414. This was converted to the triacetate and selectively deprotected to diol 415. Acid-catalyzed cycUzation and protection of the free OH group afforded the trichothecene skeleton 416. Afterwards, the acetal 416 was deprotected and the ketone was reacted in a Wittig reaction to the olefin, which was treated with TBAF to afford compound 417. Epoxidation with /n-CPBA, followed by acetylatiOTi and final mono-deprotection, afforded the trichothecene, anguidine (376) (Scheme 8.4). [Pg.79]


See other pages where Hydroxymethylene compounds acetals is mentioned: [Pg.254]    [Pg.53]    [Pg.320]    [Pg.1635]    [Pg.33]    [Pg.207]    [Pg.1356]    [Pg.64]    [Pg.408]    [Pg.491]    [Pg.617]    [Pg.304]   
See also in sourсe #XX -- [ Pg.13 ]




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Hydroxymethylene compounds

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