Benzyl-4-methoxyphenyl ketone

Electron-withdrawing groups promote anodic fluorination while electron-donating groups interfere with fluorination. In fact. bis(4-methoxyphenyl) ketone hydrazone does not give mono-fluorinated product at all, probably due to the low electrophilicity of the anodically generated benzylic cation intermediate, although the mechanism of the reaction is not clear. 

Also obtained by iodination of benzyl 2-hydroxy-3-iodo-4-methoxyphenyl ketone with iodine and iodic acid in ethanol at 60-70° overnight [5176]. 

COCH2 j - Obtained by partial methylation of benzyl 2,5-dihydroxy-4-methoxyphenyl ketone with... 

Bis(p-methoxyphenyl) telluroxide (118) and the corresponding tellurone (119) have recently been shown to exhibit mild oxidizing properties towards easily oxidizable substrates. Thus the telluroxide (118) oxidizes thiocarbonyl compounds RR C=S to the corresponding ketone RR C—O364,365 and 3,4-di-f-butylpyrocatechol to 3,4-di-f-butyl-o-quinone.364 The tellurone (119) oxidizes benzyl alcohols to the corresponding carbonyl compounds, a reaction. .which is not observed with (118).366... 

Acylation of aromatic ethers yields the corresponding keto ethers. Typical examples are found in the conversion of anisole with aluminum chloride and appropriate acyl halide to p-methoxybutyrophenone (85%) and p-methoxyphenyl benzyl ketone (84%). Mild catalysts like iodine and phosphorus pentoxide are also effective. 

Abbreviations Ac acetyl AIBN azobisisobutyronitrile All allyl Bn benzyl Bz benzoyl ClAc chloroacetyl DAST diethylaminosulfur trifluoride DBU l,8-diazabicyclo[5.4.0]-undec-7-ene DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTST dimethyl(methylthio)sulfonium trifluoromethanesulfonate Fmoc 9-fluorenyl-methoxycarbonyl HDTC hydrazine dithiocarboxylate IDCP iodonium di-collidine perchlorate Lev levulinoyl MBz 4-methylbenzoyl Me methyl MEK methyl ethyl ketone MP 4-methoxyphenyl NBS iV-bromosuccinimide NIS A-iodosuccinimide Pent n-pentenyl Pfp pentafluorophenyl Ph phenyl Phth phthaloyl Piv pivaloyl PMB 4-methoxybenzyl TBAF tetrabutylammonium fluoride TBDMS tcrt-butyldimethylsilyl TBDPS tert-butyldiphenylsilyl TCA trichloroacetyl TES triethylsilyl Tf trifluoromethanesulfonyl TMS trimethylsilyl Tol 4-methylphenyl Tr trityl Troc 2,2,2-trichloroethoxycarbonyl Ts tosyl. 

The PMB ether, also referred to as an MPM ether [(4-methoxyphenyl)methyl], is less stable to acids than a benzyl ether. Its utility as a protecting group stems from the fact that it can be removed oxidatively with DDQ (2,3-dichloro-5,6-dicyano-l,4-benzo-quinone) under conditions that do not affect protecting groups such as acetals, RO-Bn (or RO-BOM), RO-MOM, RO-MEM, RO-THP, RO-TBS, benzoyl, tosyl, or acetate groups, nor do they affect epoxides or ketones. Alternatively, RO-PMB ethers can be cleaved with (NH4)2Ce(N03)6. ... 

The acid-catalyzed hydrolyses of both cz.s-a net hole oxide (121) and trans-anethole oxide (124) yield identical product mixtures of 20% erythro and 80% threo 1 -(p-methoxyphenyl)-1,2-propanediols, suggesting that there is a common benzylic car-bocation intermediate (127) and common product-forming steps.108 These results indicate that rotation about the (%-C bond of the carbocation intermediate 127 is faster than attack of water on the carbocation. However, the ratio of diol and ketone products from the pH-independent reaction of cw-anethole oxide is very different than that from trans-anethole oxide, so rotation about the Ca-Cp bond in the transformation of 121 to 124 is not rapid compared to the rates of ketone and diol product formation. 

Also obtained by demethylation of 2-methoxyphenyl benzyl ketone (oil, b.p. gg, 130-140°),... 

Preparation by treatment of 3-benzyloxy-4-methoxyphenyl benzyl ketone (SM) with a mixture of concentrated hydrochloric acid and acetic acid (1 2 v/v) and heating at 70° for 1 h (69%) [5349]. SM was obtained by oxidation of l-(3-benzyloxy-4-methoxyphenyl)-2-phenylethanol (m.p. 79-82°) with potassium dichromate in dilute sulfuric acid at 50° for 1 h (80%, m.p. 105-106°). 

Also obtained by alkaline oxidation of 2-hydroxy-4-methoxyphenyl benzyl ketone with potassium persulfate in aqueous potassium hydroxide/pyridine mixture (Elbs reaction) [5344],... 

Also obtained by saponification of (4-acetoxy-2,6-di-methoxyphenyl) benzyl ketone (m.p. 108-110°) in ethanol with 3% aqueous sodium hydroxide on a water bath (77%) [5384]. 

Preparation by partial methylation of 2,4-dihydroxy-3-methyl-6-methoxyphenyl benzyl ketone with methyl iodide in the presence of potassium carbonate in boiling acetone for 4 h (82%) [5353]. 

Obtained by Claisen rearrangement of 4-allyloxy-2-methoxyphenyl benzyl ketone (m.p. 126-127°) either using boiling dimethylaniline or heating up to 185-190° under reduced pressure [5276]. 

Also obtained by reaction of prenyl bromide witb 2,4-dihydroxy-6-methoxyphenyl benzyl ketone in methanolic potassium hydroxide for 20 h at r.t. (20%) [5352],... 

OCH3 Obtained by methylenation of 2,4,5-tri-hydroxy-6-methoxyphenyl 4-methoxy-benzyl ketone with methylene iodide in the presence of potassium carbonate in refluxing acetone for 40 h [5525],... 

Obtained by reaction of potassium persulfate with 2,4-dihydroxy-6-methoxyphenyl 3,4,5-trimethoxy-benzyl ketone in 40% aqueous potassium hydroxide at r.t. overnight (Elbs reaction) (21%) [5559],... 

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