Accession Number:

AD0613409

Title:

ALPHA-SUBSTITUTED BETA-DIKETONES. STEREOISOMERIC ENOLS OF ALPHA-PHENACYLDIBENZOYLMETHANE. ADDITION-ENOLIZATION OF UNSATURATED TRIKETONES,

Descriptive Note:

Corporate Author:

COBB CHEMICAL LAB UNIV OF VIRGINIA CHARLOTTESVILLE

Personal Author(s):

Report Date:

1956-02-06

Pagination or Media Count:

11.0

Abstract:

The persistence and instability of metastable alpha-substituted beta-diketones are attributed to steric effects. The existence of two stereoisomeric alpha-phenacyldibenzoylmethane enols was demonstrated. One cis, crystalline was obtained by enolization of the triketone and gave a normal chelated copper derivative. The other trans, oil was obtained by conjugate reduction of tribenzoylethylene which followed a predicted sterochemical course, and gave a non-chelated complex copper salt involving four molecules of enol. Steric factors affecting the ease of furanization of the trans enol and its 3-bromo derivative are discussed. Reversible addition-enolization of tribenzoylethylene by alkoxide ion was demonstrated, and the effect of acid on competing ketonization and elimination is discussed. Trans-dibenzoylethylene is shown to undergo reversible base-catalyzed addition of alcohol under similar conditions. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE