L- ethanon

Products of a so-called vinylogous Wolff rearrangement (see Sect. 9) rather than products of intramolecular cyclopropanation are generally obtained from P,y-unsaturated diazoketones I93), the formation of tricyclo[2,1.0.02 5]pentan-3-ones from 2-diazo-l-(cyclopropene-3-yl)-l-ethanones being a notable exception (see Table 10 and reference 12)). The use of Cu(OTf), does not change this situation for diazoketone 185 in the presence of an alcoholl93). With Cu(OTf)2 in nitromethane, on the other hand, A3-hydrinden-2-one 186 is formed 160). As 186 also results from the BF3 Et20-catalyzed reaction in similar yield, proton catalysis in the Cu(OTf)2-catalyzed reaction cannot be excluded, but electrophilic attack of the metal carbene on the double bond (Scheme 26) is also possible. That Rh2(OAc)4 is less efficient for the production of 186, would support the latter explanation, as the rhodium carbenes rank as less electrophilic than copper carbenes. 

Dimethyl-1-cyclohexyl-1-trimethylsiloxy-ethene (191) gives by means of methyllithium/ethylbromide in dimethoxyethane (DME) 1-cyclohexyl-2,2-dimethyl-1-butanone (297)133 Dimerizations occur when substances such as 1-trimethylsiloxy-styrene (192) or 1-trimethylsiloxy-l-cyclopentene (195) are treated with silver oxide/ DMSO to afford l,5-diphenyl-2,5-butadione (198) and 2,2 -dicyclopentanonyl (199)l34 respectively. Under the catalytic influence of Cu2+ ions, 192 plus ben-zenesulfonyl chloride yield phenyl-(l-phenyl-l-ethanone-2-yl)sulfone (200)l3 ... 

A stirred and cooled (0°C) solution of l-(2,4-diaminophenyl)-l-ethanone in a concentrated hydrochloric acid solution, water and acetic acid was diazotated with a solution of sodium nitrite in water. After stirring at 0°C, the whole was poured onto a solution of copper (I) chloride in a concentrated hydrochloric acid solution while stirring. The mixture was heated at 60°C. After cooling to room temperature, the product was extracted twice with 2,2 -oxybispropane. The combined extracts were washed successively with water, a diluted sodium hydroxide solution and again twice with water, dried, filtered and evaporated, yielding l-(2,4-dichlorophenyl)-l-ethanone. 

There are certain situations in which, despite the general view, it seems likely that electrophilic attack on neutral pyrrole ring nitrogen does take place. One example is reaction of indole with 2,2-dichloroacetyl chloride in refluxing DCE yielding 2,2-dichloro-l-(indol-l-yl)-l-ethanone 31 in 88% yield <1997TL7813> N-deprotection of 31 is easy with EtsN at room temperature. 

Addition of fuming nitric acid (over 30min at —40°C) to a solution of 2,2,2-trichloro-l-(l//-pyrrol-2-yl)-l-ethanone in acetic anhydride, followed by stirring for 6 h at room temperature, gives 2,2,2-trichloro-l-(4-nitro-l//-pyrrol-2-yl)-l-ethanone in 70% yield <2003OBC3327>. Direct nitration of pyrroles 295 with nitric acid/trifluoroacetic anhydride affords mononitro derivatives 296 in 78-81% yield (Equation 67) <2005ARK179>. 

The vapor-phase acylation of pyrrole was carried out over zeolite catalysts such as HZSM-5(19.7), HZSM-5(30), HZSM-5(280), HY, and cation-promoted modified zeolites like CeHZSM-5(30), LaHZSM-5(30), and CeHY, in a fixed-bed reactor at atmospheric pressure using acetic anhydride as an acylating agent <1998CAL95>. The catalytic activity of the zeolite catalysts was dependent on the reaction temperature and the type of cation polymer used in the modification of the zeolite surface. The acylation was found to be more active on Br0nsted acidic sites available over zeolite systems. The yield of l-(l//-pyrrol-2-yl)-l-ethanone 376 with respect to the conversion of pyrrole on HZSM-5(280) at 250 °C was 75.5% (Equation 87). 

When pyrrole 987 was subjected to the usual reaction conditions, l-(2,3-dihydro-17/-pyrrolizin-5-yl)-l-ethanone 988 was obtained as the major product. The desired diketone 989 was isolated in very low yield together with a small amount of the unexpected sulfone 984 (Equation 234). This compound is formed by alkyl radical addition at C-5, and subsequent aromatization by the loss of an acetyl radical. When pyrrole 987 was reacted with BusSnH/AIBN in the absence of CO, dihydropyrrolizines 988 and 984 were isolated in 74% and 23% yields, respectively <2000TL3035>. 

During the design of steroid mimics as potential ACAC inhibitors, the exocyclic enone functions in 2-[4,4-bis(trifluoromethyl)-2-(4-fluorophenyl)-4,5-dihydro-l//-imidazol-5-ylidene]-l-(4-fluorophenyl)-l-ethanones 815 are selectively reduced with zinc dust to the imidazolines 816 in high yields (Scheme 202) <1996T11153>. 

Proline is a particular case in the Maillard reaction because it is, unlike other amino acids, a secondary amine. It represents an important precursor for popcom-like aroma compounds in the reaction with reducing sugars such as glucose [46]. The relevant aroma compounds in this reaction are 2-acetyl-l-pyrroline (22), l-(l,4,5,6-tetrahydro-2-pyridyl)-l-ethanone (23) and its isomer l-(3,4,5,6-tetrahydro-2-pyridyl)-l-ethanone (24) [47], The formation pathway (Fig. 3.25) shows the important intermediates 2-oxopropanal (7) and 1-pyrroline (25) [48, 49[. Another amino acid precursor for 22 is ornithine, an amino acid in yeast or yeast extracts [49[. 

Insertion of a carbene unit into the N—H bond of primary or secondary amines by copper salt catalyzed decomposition of diazo compounds has been known for a number of years The copper chelate promoted reaction of diazodiphenylmethane or 2-diazo-l,2-diphenyl-l-ethanone with primary benzylamines or N2=CPh2 R R CH-NHj Q h2CH-NCHR R J Ph C-N-CHR r ... 

A similar reaction sequence allows the preparation of symmetrical and unsyrametri-cal ketazines 318 from hydrazones and diazodiphenylmethane or 2-diazo-l,2-diphe-nyl-l-ethanone 2 . ... 

H.60) Ethanone, l-(2-hydroxyphenyl)-, l-(2-hydroxyphenyl)-l-ethanone, o-hydroxyphenyl methyl ketone, 2 -hydroxyacetophenone (at least, 2 -avoid confusion on the site of the substitution), o-hydroxyacetophenone, o-acetylphenol [118-93-4] FEMA 3548... 

H.63) (H.63) Ethanone, l-(2-hydroxy-5-methylphenyl)-, l-(2-hydroxy-5-methylphenyl)-l-ethanone. 2 -hydroxy-5 -methylacetophenone, 2-acetyl-4-methylphenol, o-acetyl-p-cresol, l-hydroxy-2-acetyl-4-methylbenzene [1450-72-2]... 

H.66) (H.66) Ethanone, l-(4-hydroxy-3-methoxyphenyl)-, l-(4-hydroxy-3-methoxyphenyI)-l-ethanone, acetovanillone (not to be confused with acetovanillin which is O-acetylvanillin), vanillone, acetoguaiacone, 4-hydroxy-3-methoxyacetophenone [498-02-2]... 

H.67) Ethanone, l-(3,4-dimethoxyphenyl)-, l-(3,4-dimethoxyphenyl)-l-ethanone, 3,4-dimethoxyphenyl methyl ketone, 3,4-dimethoxyacetophenone, acetoveratrone, 4-acetylveratrole 1131-62-0]... 

A further application of this approach is the s)mthesis of 1,2-diaryl-l-ethanones 12 in good to excellent yields by reaction of aryl acetic acids 11 with arenes in the presence of 85% phosphoric acid without solvent at 50°C for 30-180 min (Scheme 2.7). The reaction tolerates a variety of substituents, and groups such as methoxy and thiomethoxy are found to be highly effective. 

Veeramaneni, V. R., Pal, M., and Yeleswarapu, K. R. 2003. A high speed parallel synthesis of 1,2-diaryl-l-ethanones via a clean-chemistry C-C bond formation reaction. Tetrahedron 59 3283-3290. 

When 1,2-diphenyl-l-ethanone (4-19, Ar = C6H5) was used by Regitz (1964 b, 1965 b) a rather unstable intermediate and another end product were found in addition to the diazoketone 4.22 (Ar = CgHs). In our opinion there is not enough mechanistic information available for an interpretation, considering also the experience with Ny-labeled 4-toluenesulfonyl azide in the reaction with cyclopenta-dienyl anion. For these reactions Roberts and coworkers found, besides the expected diazocyclopentadiene with in the a-position, some Np-labeled product (Duthaler et al., 1978). 

In the synthesis of 173, the relative stereochemistry is set in the addition of a 4-(l-metallo-ethyl)-5-fluoropyrimidine derivative to l-(2,4-difluorophenyl)-2-(17/-l,2,4-triazol-l-yl)-l-ethanone 174 (Scheme 12.27). The diastereocontrol of this can be controlled by pyrimidine substitution pattern and reaction conditions of the metalation step. Good diastereoselectivity (12 1) is obtained using an zinc derivative of 175. After removal of the chlorine from the pyrimidine ring, of the desired stereoisomer of 173 is isolated via a diastereomeric resolution using salt (l/ )-10-camphorsulfonic acid (10-CSA). Synthetic routes to the pyrimidine partner have also been evaluated. Shown in Scheme 12.28, the initial six-step route from 5-fluorouracil 177 can be replaced by a four-step process, involving fluorination of methyl 3-oxopentanoate and cyclization with formami-dine acetate. ... 

A soln. of l-/ r/-butyldimethylsilyl-2-chloro-l-ethanone in THF added dropwise during 15 min to a stirred soln. of Li-2,2,6,6-tetramethylpiperidide in the same solvent at —78° under argon, after 30 min methyl vinyl ketone added, the mixture allowed to warm to room temp, during 1 h, and half-satd. NH4CI soln. added after a further 30 min-> l-[2-(/er/-butyldimethylsilyloxomethyl)cyclopropyl]ethan-l-one. Y 75-89% cis Jrans 1.9 1). F.e., also from a-sulfonioacylsilanes, s. J.S. Nowick, R.L. Danheiser, Tetrahedron 44, 4113-34 (1988). 

Contrast and compare the relative acidities of 1-phenyl-l-ethanone, 1-phenyl-1-propanone, 2-methyl-l-phenyl-l-propanone, and 2,2-dimethyl-l-phenyl-l-propanone. 

As shown in Scheme 1.46, a simple synthesis of complex fused 1,4-benzoxaz-epin-2-one derivatives 86 and 87 was aehieved via a three-component leaction of quinoline or isoquinoline, acetylene dicaiboxylic esters and l-(6-hydioxy-2-isopio-penyl-l-benzofman-yl)-l-ethanone in water, in the absence of aiy catalyst [68]. Presumably, this transformation proceeds via the initial formation of a 1 1 zwitter-ionic intermediate 88 from the Michael addition of isoquinohne (or quinolone) to the activated ester. A proton transfer reaction takes then place in which this species is protonatedby the phenol group in the l-(6-hydroxy-2-isopropenyl-l-benzofuran-yl)-l-ethanone substrate, and this is followed by a second Michael addition of the resulting phenoxide anion to the isoquinohnium ion to afford intermediate 88, containing benzofuryl and isoquinoline ring systems. This intermediate then undergoes... 

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