Acetophenone, 2-diazo

Bei der Reduktion von 4-Brom- cy-diazo-acetophenon, die stufenweise bis zum 4-Brom-l-phenyl-athanol lauft, kann die Zwischenstufe 2-(4-Brom-phenyl)-glyoxal-hy-drazon bei der Reduktion in Mcllvaine-Pufferlosung an Quecksilber (—0,8 V) isoliert werden1 ... 

The boron trifluoride etherate catalysed formation of oxazoles has been used in synthesis. Doyle has successfully employed the reaction in the synthesis of annuloline 20, a disubstituted oxazole isolated from the roots of the annual rye grass. Thus, l-diazo-4 -methoxy-acetophenone 19 was reacted with 3,4-dimethoxycinnamonitrile in the presence of boron trifluoride etherate to yield the natural product 20 in 48% yield (Scheme 11).<80JOC3657>... 

Acetophenone, A/-methyloxazolidine derivative, lithiation, 56, 261 Acetyl hypofluorite fluorination of uracil by, 59, 3 fluorination using, 60, 7 reaction with pyridines, 58, 280, 289 Acetylacetone, hexafluoro-, reaction with ethylenediamine, 56, 3 Acetylene cyclic dimer, trimer. tetramer, dissociation energies, 56, 343 Acetylenes, activated reactions with 3-diazo-azoles, 59, 70... 

Evans and co-workers have reported successful diazo transfer from p-nitrobenzenesulfonyl azide (PNBSA) to the enolate derivatives of an N-acyloxazolidinone and a benzyl ester (a) Evans, D. A. Britton, T. C. Ellman, J. A. Dorow, R. L. J. Am. Chem. Soc. 1990, 112, 4011. However, we have not been able to achieve efficient diazo transfer to ketone enolates employing these conditions. For example, exposure of the lithium enolate of acetophenone to 1.2 equiv of PNBSA in THF at -TS C for 15 min gave a-diazoacetophenone in only 21% yield. 

Acetophenon 4-Nitro- -hydrazon Et4b, 508 (Umhydrazonierung) Benzofurazan-l-oxid 5-Dimethyl-amino- E8c, 783 (4-NR3-2-N3-l-N02-Ar/H ) Cyclopropan 1-Azidocarbonyl-l-Cyclopropylcarbonyl- E17b, 1568 (cycl.-En-ol-ester + HN3) Essigsaure Diazo- -(2-furfuryl-methyl-amid) E14b, 1196 (OR - NR2)... 

Acetophenon a-Diazo-2,4,5-trimethoxy- E6b/1, 76 (Ar-COOH + S02C12/CH2N2) Acrylsaure 3-Anilino-2-nitro- -ethylester E15/2, 1369 [02N-CH2 COOR + R-NH2/ HC(OR)3]... 

Various organic solvents can be used, e.g. benzene, toluene, hexanes, acetone, acetophenone, diethyl ether. However, the substrate must be in large excess to the diazo compounds. The effect of additives has been examined. Pyridine or similar donor molecules retard the catalytic rates and decrease the optical yields. ... 

Aiiiino-4-phenylthiazoles, from o-diazo-acetophenone and thiourea, 231 2-Amino-5-phenylthiazole, diuretic prope ties of Schiffs bases of, 167 synthesis of, by condensation of ammonia with At(ary 1-1,3-oxathiol-2-yIidine) tertiary iminium salts. 300 2-(p-Ammophenyl) thiazoles, syntheses of, 4,5-disubstituted derivatives of, 191 2-Amino5-substituted thiazoles, from o-haloaiddiydes and thiourea, 224, 225 /V,At -bis (2-Amino-4 substituted thiazolyl)-p biphenylene, from p-biphenylene dithiourea and o-halocarbonyl compounds, 243... 

The CH2 group of co-imidazol-l-yl)acetophenone 1004 is sufficiently activated by the carbonyl and the imidazole group that it readily reacts with aldehydes, aromatic diazonium salts (to form diazo compounds) and acrylonitrile. The reaction of 1004 with phenyl isothiocyanate in the presenceof KOH results in the formation of adduct 1005 that is not isolated but further condensed with phenacyl bromide to afford thienylimidazole 1006 in 87% yield (Scheme 241) <2003SC153>. In the presence of a 2-sulfanyl group 1007, the enolate of ot-imidazolyl acetophenone 1008 no longer reacts with aldehydes or even alkyl halides except for Mel 1009 <200282691 >. 

Azide synthesis (2, 415). In the definitive paper3 describing the conversion of primary amines into azides by a diazo transfer reaction, methyllithium is preferred to methylmagnesium chloride as the base. The reaction has been extended to hydrazones. Thus, when the hydrazones of benzophenone, fluorenone, and acetophenone are treated with methylmagnesium chloride and then with tosyl azide, the corresponding diazoalkanes are obtained in about 20% yield. 

Diazo transfer from tosyl azide to diphenylphosphinoxide acetamide (33) is accomplished via 1,5 ring closure of 34 to afford 4-diphenylphosphinyl-5-hydroxy-l,2,3-triazole (35).14 However, triazole 35 is further thermally isomerized in DMF back to diazo acetamide (34). Tosyl azide in the presence of piperidine converts phosphinoxide acetophenone (36) to diazo acetophenone 37.15... 

In aqueous buffer solutions (pH 6), Bailes and Leveson (1970) observed, however, three polarographic waves in the reduction of 2-diazo-l-phenylethan-l-one (9.52). They correspond to the transfer of six, two, and two electrons, respectively, a result corroborated by controlled-potential coulometry by the same authors. These three waves are consistent with the mechanism (9-27), i. e., formation of a-aminoaceto-phenone (9.53), acetophenone (9.54), and 1-phenylethanol (9.55). Furthermore, polarography starting with the intermediates 9.53 and 9.54 gave results consistent with the waves for parts B and C of mechanism (9-27). 

Mondal" described a one-step synthesis of texamine 1173 from benzonitrile and a-diazo-(3, 4 -methylenedioxy)acetophenone using InCla. This approach is similar to Fukushima and Ibata s earlier synthesis of 2-aryl-5-phenyloxazoles (Scheme 1.37). 

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