1- Phenyl-l,4-pentanedione

Sodium, with l-bromo-3-chloro-cyclobutane to give bicyclo [l.l.O]butane, 51, 55 Sodium amalgam, 50, 50, 51 Sodium amide, with 2,4-pentane-dione and diphenyliodonium chloride to give l-phenyl-2, 4-pentanedione, 51, 128 Sodium azide, 50, 107 with mixed carboxylic-carbonic anhydrides, 51, 49 Sodium borohydride, reduction of erythro-3-methanesulfony-loxy-2-butyl cyclobutanecar-boxylate, 51, 12 reduction of 2-(1-phenylcyclo-pentyl)-4,4,6-trimethyl-5,6-dihydro-1,3(4H)-oxazine to 2-(1-phenylcyclopentyl)-4,4, 6-trimethyltetrahydro-l,3-oxazine, 51, 25 Sodium cyanoborohydride, used... 

PHENYLATION WITH DIPHENYLIODONIUM CHLORIDE l-PHENYL-2,4-PENTANEDIONE... 

When l-phenyl-2,4-pentanedione is doubly deprotonated with potassium amide in ammonia, the ensuing aldol reaction with benzophenone gives the expected aldol (19).55 However, if sodium amide is employed to generate the dianion, the reaction product with benzophenone is the dihydro-7-pyrone (20 equation 36).56 This result suggests the intermediacy in the latter reaction of a dianion involving the benzylic position. Further study of this interesting reaction is warranted. 

Ethereal acetylacetone added in small portions with Dry Ice-acetone cooling under Ng to 2 moles NaNH2 in liq. NH3, the cooling bath removed and the N2 flow stopped, after 0.5 hr. diphenyliodonium chloride added, after 1 hr. ether added while the NH3 is cautiously evaporated on a steam bath, finally the ethereal suspension refluxed 1 hr. crude l-phenyl-2,4-pentanedione. Y 92%.— The reaction of diaryliodonium chlorides with disodio-/ -diketones appears to be a good method for the prepn. of y-arylated y -diketones. F. e. s. K. G. Hampton, T. M. Harris, and G. R. Hauser, J. Org. Ghem. 29, 3511 (1964) cation specificity, monoalkylation, s. J. Org. Ghem. 30, 61 (1965) alkylation with dibromides s. J. Org. Ghem. 30, 1413. 

IODONIUM CHLORIDE 1-PHENYL-2, 4-PENTANEDIONE, 51, 128 4-Phenyl-l-carbethoxysemicar-bazide, from ethyl hydra-zinecarboxylate and phenyl isocyanate, 51, 122 with potassium hydroxide to give 4-phenylurazole, 51,... 

Phenyl-1,4-pentadiyne, 91 1-Phenyl-2,4-pentanedione, 178 p-Phenylphenol, 320 Phenylphosphorous chloride, 279 Phenylphosphorous dichloride, 323 Phenylpotassium, 346 cis-l-Phenylpropene, 280 rra/w-l-Phenylpropene, 151, 280, 281... 

Diketones cyclize much more efficiently than simple ketones. Photochemical cyclobutanol formation is the key step in a novel route14 to 1,3-cyclopentanediones, as exemplified by the conversion of l-bromo-5-phenyl-2,3-pentanedione to 4-phenyl-l,3-cyclopentanedione. 

Abbreviations used are dbm = dibenzoylmelhane tfbzac = 4,4,4-trifluorobenzoylacetone tta = thenoyltrifluoroacetone tc-bzac = 2-thiocyanato-l-phenyl-l,3-butane-dione br-dbm = 2-bromo-l,3-diphenyl-l,3-propanedione n-acac= 3-nitro-2,4-pentanedione tc-acac = 3-thio-cyanato-2,4-pentanedione br-acac = 3-bromo-2,4-pentanedione. 

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