Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Ketone moiety

In a related reaction, a number of aryloic compounds, behaving as ketonic moieties in the Fischer indolisation, have been shown to afford carbazoles in the Japp-Maitland condensation. For example, when either I-naphthol, 2-naphthol, 6-alkyl-2-naphthol, ... [Pg.113]

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-... [Pg.237]

Virus replication comprises numerous biochemieal transformations that might provide suitable targets for antiviral therapy. The antiviral effect of thiosemicarbazones was first demonstrated by Hamre et al. [53, 54], who showed that p-aminobenzaldehyde-3-thiosemicarbazone and several of its derivatives were active against vaccinia virus in mice. These studies were extended to include thiosemicarbazones of isatin, benzene, thiophene, pyridine, and quinoline derivatives, which also showed activity against vaccinia-induced encephalitis. The nature of the aldehyde/ketone moiety was not as significant as the presence of the thiosemicarbazide side chain the latter was deemed essential for antiviral activity. [Pg.7]

The conversion of 27 to chiral hydroxy acid 26 was envisioned to arise via a sequential reduction protocol where the ketone moiety of 27 would enantioselectively be reduced to give chiral allylic cyclopentenol 46 (Scheme 7.11). Subsequent 1,4-addition of hydride to the a,/J-unsaturated ester of 46, presumably assisted by... [Pg.199]

Ge. Scandium(III) triflate-catalyzed allylation of carbonyl compounds with tetraallylgermane proceeded readily in aqueous nitromethane to afford homoallyl alcohols in excellent to good yields.175 The presence of H20 is indispensable for the allylation of aldehydes to proceed smoothly. Aldehydes were allylated exclusively in the presence of ketone moieties (Eq. 8.74). [Pg.254]

Thiosemicarbazones attached to an amide moiety rather than an aldehyde or ketone moiety show better solubility. For example, the Ni11 complex with 2-pyridineformamide N(4)-methylthio-semicarbazone is square planar with N,N,S ligand coordination.1251 The coordination sphere is completed by an O-bound acetate coligand. [Pg.356]

If the arylation chemistry is carried out under 1 atm of CO, an isoquinoline with a ketone moiety in the 4 position is produced in good yields (Scheme 10).11... [Pg.438]

We have also examined the behavior of copolymers of o-tolyl vinyl ketone and methyl vinyl ketone (CoMT). In this case the light is absorbed exclusively at the aromatic carbonyl chromophore and the reaction proceeds from this site, while the methyl vinyl ketone moieties provide a relatively constant environment but prevent energy migration along the chain. The values of Tg and Tip in benzene have been included in Table II. These copolymers axe also soluble in some polar solvents for example, we have used a mixture of acetonitrile acetone methanol (30 30 Uo, referred to as AAM). This mixture is also a good solvent for the electron acceptor paraquat (PQ++) which has been shown to be good biradical trap in a number of other systems (9.). [Pg.23]

Twofold Michael additions have been utilized by the groups of Spitzner [2] and Hagiwara [3] to construct substituted bicyclo[2.2.2]octane frameworks. In Hagiwara s approach towards valeriananoid A (2-6) [4], treatment of trimethylsily-enol ether 2-2, prepared from the corresponding oxophorone 2-1, and methyl acrylate (2-3) with diethylaluminum chloride at room temperature (r.t.) afforded the bicyclic compound 2-4 (Scheme 2.2). Its subsequent acetalization allowed the selective protection of the less-hindered ketone moiety to provide 2-5, which could be further transformed into valeriananoid A (2-6). [Pg.49]

Chalcones (including 11) contain a l,3-diaryl-a,/)-unsaturated ketone moiety and have anti-cancer properties [38]. As analogs of CA-4, 7, the mode of cytotoxic action of chalcones has been shown to be similar to the com-bretastatins. They bind to the colchicine site of tubulin and inhibit tubulin polymerization [39]. [Pg.19]

Hydrative cyclization of diynes with ruthenium catalyst has been reported for the synthesis of sulfolenes or enones in aqueous medium.381 Reactions of unsymmetrical 1,6-diynes have been investigated, and some substrates are found to exhibit a directing effect of the ketone moiety in a pendant group. [Pg.356]

The high enantioselectivity shown in the above reactions can be attributed to two important factors. First, coordination of the Lewis acid with the a-hydroxy ketone moiety of dienophile 17 or 19 leads to the formation of a rigid five-membered chelate 21. This chelate causes the differentiation of the two dia-stereotopic faces of the enone system. Second, arising from the established absolute configuration of 17 and 19, within 21, the Diels-Alder reaction proceeds with the enone fragment at its cisoid position (yyu-planar). [Pg.272]

Scheme 11.31. The transformation of an ester group in 118 into a vinyl ketone moiety in the preparation of the anti-diol 122 [76],... Scheme 11.31. The transformation of an ester group in 118 into a vinyl ketone moiety in the preparation of the anti-diol 122 [76],...
A palladium-catalyzed three-component assembly process of an aryl iodide, carbon monoxide and allene offers a facile synthesis of heterocycles bearing an a-exo-methylene ketone moiety (Scheme 16.10) [15, 16]. [Pg.928]

Triethylamine as the electron donor was also used by Mattay and co-workers in tandem fragmentation cyclization reactions of a-cyclopropylketones. The initial electron transfer on the ketone moiety is followed by the fast cyclopropyl-carbinyl-homoallyl rearrangement, yielding a distonic radical anion. With an appropriate unsaturated side chain within the molecule both annealated and spi-rocyclic ring systems are accessable in moderate yields (Scheme 41) [62]. [Pg.209]

An alternative route to dibenzothiophenebut3o ic acids has been developed involving reaction of 4-lithiodibenzothiophene with menthyl levulate, yielding, after ester hydrolysis, y-hydroxy-y-methyl-4-dibenzothiophenebutyric acid (139). The bulky menthyl group was employed to direct reaction to the ketone moiety of the levulate. Dehydration followed by catalytic hydrogenation yields y-methyl-4-dibenzothiophenebutyric acid, Friedel-Crafts cyclization of which yielded the ketone (140). ... [Pg.278]

Replacing the electrophilic epoxy ketone moiety in TPX by a reversible zinc chelator such as a hydroxamic acid was carried out by Yoshida et al. (Fig. 6) [51]. This modification led to a low nanomolar reversible inhibitor of the HDACl enzyme. Several other cyclic tetrapeptides containing the epoxyketone feature, such as chlamydocin, were converted into their hydroxamic acid coimterparts as well [52]. Additionally, the introduction of reversed hydroxamic acids (-N(OH)COR, with R = H or Me) onto the structure of Cyl-1 was reported to give potent HDAC inhibitors as illustrated in Fig. 6 [53]. Generally, the most potent inhibitors were the examples with R = H and m = 2. Apicidin, a cychc peptide more remotely related to TPX, exhibits potent antiprotozoal activity via HDAC inhibition in parasites [54]. [Pg.304]

Levulinic acid. Hydrogenation of levulinic acid resulting in the reduction of the ketone moiety leads to 4-hydroxy pentanoic acid. This acid can cyclize to form y-valerolactone (GVL) which is a useful industrial solvent. A 94% yield of GVL was obtained with a Raney nickel catalyst, and a hydrogen pressure of 5 MPa at a temperature of 100-150... [Pg.42]


See other pages where Ketone moiety is mentioned: [Pg.176]    [Pg.209]    [Pg.253]    [Pg.79]    [Pg.600]    [Pg.1042]    [Pg.200]    [Pg.1042]    [Pg.140]    [Pg.697]    [Pg.797]    [Pg.421]    [Pg.373]    [Pg.109]    [Pg.447]    [Pg.483]    [Pg.253]    [Pg.71]    [Pg.284]    [Pg.118]    [Pg.253]    [Pg.74]    [Pg.1427]    [Pg.269]    [Pg.276]    [Pg.399]    [Pg.173]    [Pg.604]    [Pg.375]    [Pg.963]    [Pg.130]    [Pg.99]   
See also in sourсe #XX -- [ Pg.206 ]




SEARCH



Heterocyclic ketone moiety

Phenyl ketone moiety

Unsaturated ketone moiety

© 2024 chempedia.info