1-Phenylpentane-1,2-dione

Boron trifluoride etherate, is also a good catalyst for this hydride transfer to chalcone. Unlike triphenylmethyl perchlorate, however, chalcone is able to enter Michael additions with the 1,5-diketone followed by eliminations leading to unexpected products, e.g., 3-benzyl-2,4,6-triphenylpyrylium from 2-carbethoxy-l,3,5-tri-phenylpentane-l,5-dione and chalcone the benzyl group originates from chalcone, the elimination product being ethyl benzoylacetate. ... 

Simultaneous ring-chain and keto-enol tautomeric equilibria were observed (90ZOR2489) in solutions of 5-hydroxy-5-phenylpentane-2,4-dione 29. Increase of the solvent polarity and proton-accepting ability in the series... 

Finally, [Method (c)], treatment of an internal alkyne with potassium permanganate under PTC conditions leads to a good yield of a 1,2-diketone.146 The reaction probably proceeds via hydroxylation of the triple bond, tautomeric rearrangement to the a-ketol, and oxidation to the diketone. The reaction is illustrated by the conversion of 1-phenylpent-l-yne to l-phenylpentane-1,2-dione (Expt 5.101). 

The 1,3-dipolar cycloaddition of the carbonyl ylide (31) to the aldimine (32) produces the adduct (33), which has been used to synthesize the taxol C(13) side-chain (34), which is known to be required for the antitumour activity of taxol (Scheme 9).35 The dirhodium tetraacetate-catalysed decomposition of l-diazo-5-phenylpentane-2,5-dione (35) yields the carbonyl ylide (36), which cycloadds to methylenecyclopropanes (37) to produce spirocyclopropanated 8-oxabicyclo[3.2.1]octan-2-ones [(38)-(40)] in 6-75% yields (Scheme 10).36 The 1,3-dipolar cycloadditions of aliphatic or alicyclic thiocarbonyl ylides with thiobenzophenone produce both regioisomeric 1,3-dithiolanes as expected. However, in the case of highly sterically hindered thiocarbonyl ylides, methylene transfer leads to the formation of 4,4,5,5-tetraphenyl-l,3-dithiolane.37,38... 

Moreover, the synthesis and good stability of the covalent carbon-bismuth compound in the case of acetone, 2-oxopropyltriphenylbismuthonium perchlorate, excluded this type of intermediate as a common pathway, although this view was questioned by Suzuki et The reaction of the sodium salt of acetylacetone with triphenylbismuth dichloride led to a bismuthonium salt (37) decomposing slowly at room temperature to give eventually 3-phenylpentane-2,4-dione (35). ... 

The attempt to substitute the thallium moiety of phenylthallium diacetate with acetylacetone failed to give the 3-phenylpentan-2,4-dione. Instead, the presence of the disproportionation product (120) of the thallium reagent was detected by... 

A solution of acetylacetone (0.15 g, 1.5 mmol) in anhydrous benzene or dichloromethane (7.5 ml) was stirred under argon in the presence of triphenylbismuth carbonate (1.9 g, 3.8 mmol) until the reaction is complete. The reaction mixture was filtered though Celite, the filtrate was evaporated, and the residue was purified by preparative thick layer chromatography or column chromatography to give 3-phenylpentane-2,4-dione (0.10 g, 38% yield) and 3,3-diphenylpen-tane-2,4-dione (0.15 g, 40% yield) [85JCS(P1)2667]. 

Phenylpentanoic acid, A49.9, A"46 Pyrethrolone, T17.4 Isopyrethrolone, T17.2 2-Hydroxy-2-phenylpentan-3-one, A51.5 9-Methyl-A -octalin-l,6-dione, A 38.10 2-Ethyl-3-phenylpropionic acid, A"48.17 Homoadamantane-2,7-dione, X"10.8... 

The oxidative coupling of pinacolone with lead dioxide in toluene affords not only the expected dimer, 2,2,7,7-tetramethyloctane-3,6-dione, but also a cross-coupled product, 4,4-dimethyl-l-phenylpentan-3-one, and bibenzyl (Scheme 99). ... 

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