4- Methylphenyl benzyl ketone

Thus, upon photolysis of dibenzyl ketone (11) in micelles, 4-methylphenyl benzyl ketone (12) is formed as a side product according to Scheme 3. 

Also obtained by hydrolysis of 2-difluoroboryloxy-4-methylphenyl benzyl ketone (SM) (m.p. 125-126°) with refluxing dilute ethanol for 15-20 min. SM was prepared by action of phenylacetic acid with m-cresol in the presence of boron trifluoride etherate for 30 min at 125-130° (50%) [5309],... 

Obtained by nitration of 2-hydroxy-5-methylphenyl benzyl ketone,... 

Preparation by demethylation of 2-hydroxy-4-methoxy-3-methylphenyl benzyl ketone with hydriodic acid in refluxing acetic anhydride (125-135°) for 2 h (64%) [5319]. 

Also obtained by partial methylation of 2,4,6-trihydroxy-3-methylphenyl benzyl ketone with dimethyl sulfate or with an excess methyl iodide in the presence of potassinm carbonate in refluxing acetone for 3 h [5353],... 

Ethoxyvinyl trifluoromethyl ketone 243 reacts slowly at elevated temperature with aryl and benzyl azides to provide triazoles 245 in good yield (51-88%). The reactions, carried out neat, are completed usually in 2-3d(days). However, a longer reaction time (6 d) is required for 2-methylphenyl azide due to its steric hindrance. 5-Ethoxytriazolines 244, the expected intermediates in this process, readily eliminate ethanol under the reaction conditions and cannot be isolated (Scheme 34) <2002JFC(116)81 >. 

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. 

Preparation of Ketones. l-[(Trimethylsilyl)methyl]benzo-triazole reacts readily with acyl chlorides to provide the corresponding (benzotriazol-l-yl)methyl ketones in good yields. One example of such reactions is given in eq 1, and similar results are reported for reactions with benzoyl, acetyl, phenylacetyl, and other acyl chlorides. As shown by an example in eq 2, the benzo-triazolyl moiety in (benzotriazol-l-yl)methyl ketones is easily removed by reduction with zinc in acetic acid to provide the corresponding methyl ketones. To prepare higher ketones, lithi-ated l-[(trimethylsilyl)methyl]benzotriazole is alkylated first and then subjected to the regular reactions with acyl chlorides and zinc. Thus, in a reaction of l-[(trimethylsilyl)methyl]benzotriazole with -BuLi followed by benzyl bromide, l-[ l-(trimethylsilyl)-2-phenylethyljbenzotriazole is obtained in 81% yield. Subsequent treatment of this product with 4-methylbenzoyl chloride and then with zinc in acetic acid provides 4-methylphenyl 2-phenylethyl... 

OCH3 Obtainedby reaction of benzyl bromide with 2,4-dihydroxy-6-methoxy-3-methylphenyl 4-methoxybenzyl ketone in the presence of potassium carbonate in boiling acetone for 3 h (77%) [5488]. 

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