Phenyl ketone moiety

The relationship between structure and photoinitiation activity has been examined for polymeric systems bearing side-chain 1-substituted cyclohexyl-phenyl ketone moieties in the UV curing of the HDDA/BA equimolar mixture [19,20]. Indeed, the activity of poly[(l-acryloxycyclohexyl)phenyl ketone] [poly (APK)] and styrene/4-chloromethyl-styrene/l-(4-styrylmethyloxy)cyclohexyl phenyl ketone copolymers (PABOK) has been compared with that of the corresponding low-molecular-weight structural models such as 1-hydroxy-cyclohexyl phenyl ketone (HPK), 1-acetoxy-cyclohexyl phenyl ketone (ACPK) and l-(4-isopropyl-benzyloxy) cyclohexyl phenyl ketone (PIBOK). 

Polysiloxane photoinitiators containing terminal and side-chain alkyl phenyl ketone moieties (PSCPKl, PSCPK2 and PSAPK) have also been prepared and used for promoting the polymerization of MMA under UV irradiation [86] ... 

An improved method for the preparation of a series of oxazole-containing dual PPARa/y agonists was reported by A.G. Godfrey et al. The synthesis utilized the Dakin-West reaction which allowed the introduction of a phenyl ketone moiety. This ketone was subsequently converted to the corresponding oxazole using POCI3/DMF. 

Replacement of the methyl ketone moiety in 78 by a phenyl sulfoxide, interestingly, leads to a relatively potent uricosuric agent with diminished antiinflammatory action. This effect in lowering serum levels or uric acid leads to the use of this drug in the treatment of gout. Alkylation of diethyl malonate with the chlorosulfide, 79, gives the intermediate, 80. The pyrazolodione (81) is prepared in the usual way by condensation with hydrazobenzene. Careful oxidation of the sulfide with one equiv-... 

It should be mentioned in connection with the use of 119 and its etherates that conversions of alkyl phenyl ketones to the corresponding carbinols were approximately 90%, and addition and enolization were not significant. Rates of reductions were found to be lower in the ether solvents, particularly THF, than in pentane (157). The decrease has been attributed to competition between ether and ketone for the aluminum moiety (eq. [32]). 

Another convenient method for the preparation of functionalized cyclobutanol derivatives is by treatment of 1,2-diphenylethylene acetals containing a 1,3-dithiane moiety in the y-position, e.g. 14c. with butyllithium. The isolation of 2,2-(propane-l,3-diyldisulfanyl)cyclobutanol (15c) together with benzyl phenyl ketone in 90 and 92 % yield, respectively, indicates that the reaction mechanism should involve the intramolecular attack of the metalated dithiane on the acetal carbon atom with concomitant hydride shift at the acetal group.15... 

From a systematic study of bichromophoric compounds 97-99, the importance of substituents and solvent polarity in intramolecular deactivation processes of photoexcited anthracenes by nonconjugatively tethered, and spatially separated, aromatic ketones in their electronic ground state is apparent. For 97a-d, in which the electron acceptor properties of the aromatic ketone moiety have been varied by appropriate p-substitution of the phenyl ring (R is methoxy, H, phenyl, and acetyl, respectively), the longest-wavelength absorption maximum band lies at 388 nm, i.e., any ground state effects of substitution are not detectable by UV spectroscopy. Also, the fluorescence spectra of 97a-d in cyclohexane are all related to the absorption spectra by mirror symmetry. However, the fluorescence quantum yields for 97a-d in cyclohexane dramatically are substituent dependent (see Table 19), ranging from 0.20 for the methoxy derivative to 0.00059 for the acetyl compound [33,109],... 

The photocyclization of o-alkoxy phenyl ketones to yield benzofuranols (57 and 58) represents one of the earliest example of 8-H-abstraction from the lowest n, n triplet Wagner et al. [18] have provided detailed photokinetic data studying the photocyclization of a variety of o-alkoxyphenyl ketones 56, and have revealed that quantum efficiency for cyclization for 56d was the lowest (0.023) and that for 56f the highest (1.00). The diastereoselectivity for cyclization of 56 was found to be higher in benzene and lower in polar solvents. From the estimated kH values (0.6-25 x 106 s 1), it was inferred that the low rate constant for 56e (8 x 106 s ) compared to that for 56g (25 x 106s 1) i s due to the alkyl chain in the alkoxy groups that points away from the o-carbonyl moiety in the most populated equilibrium conformations (Table 8.1). 

Reactions of unsymmetrical methylene 1,3-dicarbonyl compounds with enol ethers have been investigated by Yamauchi et al. [137]. As we have mentioned earlier, the a,/ -unsaturated ketone moiety in alkylidene-/ -ketoesters reacts exclusively as the oxabutadiene. However, high regioselectivity is also observed with mixed alkyl-phenyl-1,3-diketones with exclusive reaction of the aliphatic carbonyl group, whereas in alkylidene-1,3-dicarbonyl compounds bearing an aldehyde and a keto-moiety, the a,/J-unsaturated aldehyde reacts preferentially as oxabutadiene, but not exclusively [130a]. 

Acetophenones and benzyl phenyl ketones are arylated not only on the a-posi-tion, but also on the two orfho-positions using excess aryl bromides (Eq. 63) [129]. The reaction proceeds via a-arylation (see Sect. 2.2) followed by aromatic arylation. The latter seems to occur via coordination of the enolate oxygen to arylpalladium species, as in the reaction of 2-phenylphenols and 1-naphthols (Eqs. 56-58). Benzanilides are similarly diarylated on the benzoyl moiety using aryl bromides or triflates (Eq. 64) [130]. AT-Arylation [ 131 ] is not observed under the given conditions. 

Analogous to what has been established [70] for HPK, UV irradiation should also induce in the abovementioned cyclohexyl phenyl ketone derivatives a Norrish I type fragmentation, i.e. a-cleavage with respect to the benzoyl moiety (Scheme 19) ... 

Table 16. UV curing in film matrix of the HDDA/BA equimolar mixture, under nitrogen, by low- and high-molecular-weight photoinitiators based on cyclohexyl phenyl ketone (CPK) moieties [19,20]...

Table 17. Triplet life-time (t) of polysiloxanes containing cyclohexyl phenyl ketone as well as alkylphenone moieties and polymerization rate (Rp) of MMA in the presence or in the absence of A-methyldiethanolamine [86]...

More detailed investigations on the photoreactive behaviour of polymeric systems based on the benzoin moiety have been described [103]. Indeed, poly (benzoin acrylate) [poly(AB)] and copolymers of benzoin acrylate with styrene or MMA [poly(AB-co-St) and poly(AB-co-MMA), respectively] have been prepared and characterized. Poly(AB), when irradiated by UV light in the presence of photosensitizers such as benzophenone, /r-beiraxpiinone or methyl phenyl ketone, gives a benzene-insoluble crosslinked polymer. 

A further interesting feature of the polymeric photoinitiators is based on the possibility of anchoring different photosensitive moieties to the same macromolecule in order to provide a synergistic effect on activity due to their interaction along the polymer chain. In this context, the synthesis of several copoly-meric photoinitiators bearing side-chain thioxanthone and hydroxyalkylphenone or morpholino ketone moieties has been reported recently [156]. In particular, the free radical copolymerization of 2-[2-(acryloyloxy)ethylthio] thioxanthone (AETX) with either [4-(2-acryloyloxyethoxy)phenyl]-2-hydroxy-2-propyl ketone (HPA) or [4-(2-acryloyloxyethylthio)phenyl]-2-(iV-morpholino)-2-propyl ketone (APMK) [poly(AETX-co-HPA) and poly(AETX-co-APMK), respectively] and of 4-[2-(methacryloyloxy)ethoxycarbonyl] thioxanthone (METX) with APMK [poly(METX-co-APMK)] has been performed. 

In parallel, Scherf et al. [128] have also reported a ladder-type polymer containing carbazole moieties. Their strategy is quite similar to those presented above the authors copolymerized the carbazole moiety with a phenyl bearing two benzoyl side chains. After the polymerization is completed, the ketone moieties located on the phenyl are reduced into alcohol groups by a reaction with MeLi. The ring-closure reaction of the polyalcohol was carried out by treatment with boron trifluoride etherate, affording the ladder polymer. 

If other reactive moieties are present a cyclopropanecarbonyl compound can be converted to the corresponding cyclopropylalkane using various conditions. Thus, 3,4-benzotricy-clo[4.3.1.0 ]dec-3-en-2-one yielded 3,4-benzotricyclo[4.3.1.0 ]dec-3-ene in excellent yield on treatment with sodium in liquid ammonia. di-l-Methylcyclopropane-l,2-dicarboxylic anhydride underwent a similar reaction to afford isomeric lactones on treatment with lithium aluminum hydride or sodium borohydride in tetrahydrofuran. On the other hand, ionic hydrogenation (triethylsilane in trifluoroacetic acid and water) of cyclopropyl phenyl ketone gave a complex reaction mixture and very little benzylcyclopropane. ... 

Cyclobutane formation, occasionally in fairly low yield due to ring-opening reactions, also occurred by photochemical [2 - - 2] cycloaddition of vinylcyclopropane derivatives to an a, -unsaturated ketone moiety, " a cyclobuta-1,3-diene, a 1,4-benzoquinone, 2-acylthiophenes, and on irradiation of e t/o,enr/o-2,4-bis[( )-2-(methoxycarbonyl)vinyl]bi-cyclo[1.1.0]butane. A formal [2-1-2] cycloaddition also occurred on reaction of tricyclo[3.1.0.0 ]hex-3-ene with methyl 6-oxo-5-phenyl-l,3,4-oxadiazine-2-carboxylate to give methyl 9-oxo-10-phenyl-8-oxapentacyclo[4.4.0.0 ". 0 .0 °]decane-7-carboxylate, albeit in very low yield, after nitrogen extrusion. ... 

Subsequent work has shown that the presence of an alkyl substituent a to the ketone carbonyl is crucial for the intramolecular five-membered-ring cyclization to occur. Thus, jS-hydroxy cyclopentanones can be synthesized from ketones containing both methyl and cyclopropanol moieties a to the carbonyl by treatment with sodium hydride at 0-25 °C. In the case of phenyl ketone, further retro-aldol ring scission leads to the 1,4-diketone as the only product. A retro-aldol/re-aldol sequence occurs when the methyl substituent is replaced by a longer alkyl substituent, such as an allyl group. In this case, the allyl substituent is located 7 to the carbonyl of the final product. ... 

Xanthochymol (138), to our knowledge, is the only benzophenone analyzed, in detail, for its electron impact MS fragmentation behavior [110]. Reported MS losses for benzophenones include an m/z 105 (CsHs-CO4) for a unsubstituted phenyl ketone A-ring [44,65], m/z 137 (G,H O3-CO4) for a 3,4-dihydroxybenzophenone moiety, and m/z 68 (CsHg) for a prenyl-type group. 

Dimethoxy-l,3,5-triazin-2-yloxy)phenyl phenyl ketone 60, crystallizes with two crystallographically independent molecules in the asymmetric unit (Figure 24). The two molecules adopt different conformations with respect to the geometric relations between the phenyl ketone and triazine moieties <2003AXC687>. 

Scheme 7.12 Generation of pendant macroradicals acting as precursors for the cross-linking of an EPDM elastomer containing ethylidene norbornene moieties (other comonomer moieties are not shown). Initiator hydroxycyclohexyl phenyl ketone [33].

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