Heptanediones

Difunctional target molecules are generally easily disconnected in a re/ro-Michael type transform. As an example we have chosen a simple symmetrical molecule, namely 4-(4-methoxyphenyl)-2,6-heptanedione. Only p-anisaldehyde and two acetone equivalents are needed as starting materials. The antithesis scheme given helow is self-explanatory. The aldol condensation product must be synthesized first and then be reacted under controlled conditions with a second enolate (e.g. a silyl enolate plus TiCl4 or a lithium enolate), enamine (M. Pfau, 1979), or best with acetoacetic ester anion as acetone equivalents. 

Sabinene is a monoterpene found in the oil of citrus fruits and plants It has been synthe sized from 6 methyl 2 5 heptanedione by the sequence that follows Suggest reagents suitable for carrying out each of the indicated transformations... 

A mixture of 3,5-heptanedione (61, 14.1 g, 0.11 mol) and freshly distilled aniline (1, 9.3 g, 0.1 mol) was boiled under gentle reflux for 1.5 hrs. and allowed to cool. Distilled water (50 mL) was added and the product was extracted with benzene and dried over anhydrous magnesium sulphate. Removal of the solvent left anil 62, 16 g, 81% yield, as a yellow oil which was used directly in the next stage without further purification. 

Intramolecular aldol cyclization of 2,5-heptanedione with aqueous NaOH yields a mixture of two enone products in the approximate ratio 9 1. Write their structures, and show how each is formed. 

Treatment of the minor product formed in the intramolecular aldol cyclization of 2,5-heptanedione (Problems 23.30 and 23.31) with aqueous NaOH converts it into the major product. Propose a mechanism to account for this base-catalyzed isomerization. 

CONVERSION OF NITRO TO CARBONYL BY OZONOLYSIS OF NITRONATES 2,5-HEPTANEDIONE... 

B. 2,5-Heptanedione. Methanolic sodium methoxide [Methanol, sodium salt] is prepared by cautiously adding small pieces of freshly cut sodium (5.67 g., 0.247 mole) to 200 ml. of cold methanol (Note 3) in a 500-ml., three-nccked flask equipped with a mechanical stirrer, a... 

Europium, tris(2,2,6,6-tetramethyl-3,5-heptanedione-quinuclidine)-stereochemistry, 1, 81 Europium complexes... 

Terbium, tris(2,2,6,6-tetramethyf-3,5-heptanedione)-photosubstitution, 1,408 Terbium complexes f5-diketones, 3, 1081... 

SULFIDE CONTRACTION via ALKYLATIVE COUPLING 3-METHYL-2.4-HEPTANEDIONE... 

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