9-Acetylanthracene

For the acylation of naphthalene, the ionic liquid gives the highest reported selectivity for the 1-position [95]. The acetylation of anthracene at 0 °C was found to be a reversible reaction. The initial product of the reaction between acetyl chloride (1.1 equivalents) and anthracene is 9-acetylanthracene, formed in 70 % yield in less than 5 minutes. The 9-acetylanthracene was then found to undergo diacetylation reactions, giving the 1,5- and 1,8-diacetylanthracenes and anthracene after 24 hours (Scheme 5.1-64). 

This was confirmed by taking a sample of 9-acetylanthracene and allowing it to isomerize in the ionic liquid. This gave a mixture of anthracene, 1,5-diacetylan-thracene and 1,8-diacetylanthracene. It should be noted that a proton source was needed for this reaction to occur, implying an acid-catalyzed mechanism (Scheme 5.1-65) [95]. 

In the case of the free 9-acetylanthracene anion-radical, the spin density on the carbonyl group is lower than that in the para position (position 10) by a factor of 5. The formation of the tail-to-tail dimer should be expected. Actually, preparative reduction of 9-acetylanthracene in DMF against the background of a tetrabutylammonium salt results in the tail-to-tail dimer with the yield of 70%. Addition of a lithium salt, however, decreases the dimer yield to 45% (Guftyai et al. 1987b, Mendkovich et al. 1991). 

Scheme 5.1-65 Proposed mechanism for the isomerization of 9-acetylanthracene in [EMIM]CI/AICl3 (X(AICl3) =0.67).

The product is digested under reflux for about 20 minutes with 100-150 ml. of boiling 95% ethanol. The suspension (Note 3) is then cooled quickly almost to room temperature and filtered rapidly with suction to remove any anthracene. The 9-acetyl-anthracene, which separates in the filtrate, is redissolved by heating and allowed to crystallize by slowly cooling the solution (finally to 0-5° in an icebox) (Note 4). A second recrystallization from 95% ethanol yields 35-37 g. (57-60%) of light-tan granules of 9-acetylanthracene melting at 75-76° (Note 5). 

Acetylanthracene, 30,1 Acetylation, of 2- -acetylphenylhydro-quinone, 34, 1 of hydrogen sulfide, 31, 105 a-Acetyl-7-butyrolactone, 31, 74 Acetyl chloride, 30, 1 (X-ACETYL-5-CHLORO-7-VALEROLACTONE, 31, 1... 

When the anthracene chromophore is substituted at the 9-position by a re-system, coplanarity of the two re-systems will be impaired for steric reasons, and so will be electronic conjugation. For example, in ground state 9-phenylanthracene the angle between the plane of the anthracene and that of the phenyl group is about 60° [17,18]. Likewise, in 9-acetylanthracene, the... 

Interestingly, when the precatalyst RuCl2[(5 )-Tol-BINAP][(S,5)-DPEN] (Tol = d-CeELi-Me) was employed in the reduction of 9-acetylanthracene the enantioselectivity was only 40% (equation 11). In contrast, use of RuCl2 [(/ )-Tol-BINAP][(5,5)-DPEN] resulted in a reduction of the ketone with 81% ee. Employing racemic Tol-BINAP and (5,5 )-DPEN gave (/f)-alcohol with essentially the same enantioselectivity as the enantioenriched (/f)/(5, 5 )-catalyst. 

It is noteworthy that in the reduction of F-acetyhiaphthone the catalyst with the (5 )/(5,5)-configuration was the fastest and most enantioselective while in the hydrogenation of 9-acetylanthracene the catalyst with the (/f)/(5, 5 )-configuration gave the highest enantioselectivity, and exhibited a higher turnover frequency. 

In all cases, except for 9-acetylanthracene, both Cs-symmetric amine clathrochelates with apical aromatic substituents and Ca-nonsymmetric imine sarcophaginates with substituents in the methylene units have been formed (Scheme 59). The reaction of 9-acetylanthracene under the same conditions led only to the aroyl-type sarcophaginate, since in this case a bulky substituent inhibits the condensation of a keto group with an amino group to give imine. 

The first attempt to imprint a metal complex with a reaction intermediate coordinated to the metal center was reported by Mosbach and coworkers [51], A Co monomer coordinated with dibenzoylmethane, which is as an intermediate for the aldol condensation of acetophenone and benzaldehyde, was tethered to a styrene-DVB copolymer matrix. After, the template, dibenzoylmethane was removed from the polymer, the resulting molecularly imprinted cavity had a shape similar to the template due to the interaction of the template with the polymerized styrene-DVB monomers through n-n stacking and van der Waals interactions. The rate of aldol condensation of adamantyl methyl ketone and 9-acetylanthracene was lower than the rate of condensation with acetophenone, indicating some degree of increased substrate selectivity. This is the first known formation of a C-C bond using a molecularly imprinted catalytic material. 

N-Acetylamino-L-tryptophane, 530 17a-Acetyl-A -androstene-3/5,l 7 S-diol, 660 9-Acetylanthracene, 27, 131 a-Acetyl-T-butyrolactone, 676 Acetyl chloride, 11, 263-264, 275, 336 2-, 4-, and 5-Acetylchrysene, 676-677 S-Acetylcoenzyme A, 1157... 

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