Aromatic moieties

Figure Bl.11.7. chemical shifts in [10]-paracyclophane. They have values on either side of the 1.38 ppm found for large polymethylene rings and, thus, map the local shielding and deshielding near the aromatic moiety, as depicted in the upper part of the figure.

As mentioned previously, cellulosic phases as well as amylosic phases have also been used extensively for enantiomeric separations more recently (89,90). Most of the work ia this area has been with various derivatives of the native carbohydrate. The enantioresolving abiUties of the derivatized cellulosic and amylosic phases are reported to be very dependent on the types of substituents on the aromatic moieties that are appended onto the native carbohydrate (91). Table 3 fists some of the cellulosic and amylosic derivatives that have been used. These columns are available through Chiral Technologies, Inc. and J. T. Baker, Inc. 

Synthesis and Properties. Polyoxadia2oles containing aromatic moieties with aUphatic linkages/groups have been widely explored in the hterature. The aromatic moieties increase the rigidity of the polymer the presence of aUphatic groups makes the chain more flexible and processible. 

R = an aromatic moiety, = H, and R" = R" = CH ), which were expected to have a long-hved acyl enzyme species (26) that would react further to give inactivated enzyme. The compounds all act as P-lactamase inhibitors but they are poor synergists. Aged solutions of c1oxaci11in sulfone, where... 

A fully unsaturated tricyclic indole derivative serves as the aromatic moiety for a nonsteroid antiinflammatory agent. Preparation of this compound starts with the Michael addition of the anion from methyl diethylmalonate to cyclohexanone. The product (32) is then hydrolyzed and decarboxylated to give ketoester 33. Fischer condensation with p-chlorophenylhydrazine leads to the indole This is then esterified (35) and dehydrogenated to the carbazole 36. Saponification leads... 

An isoindol1 none moiety forms part of the aromatic moiety of yet another antiinflammatory propionic acid derivative. Carboxylation of the anion from -nitro-ethylbenzene (45) leads directly to the propionic acid (46). Reduction of the nitro group followed by condensation of the resulting aniline (47) with phthalic anhydride affords the corresponding phthalimide (48). Treatment of that intermediate with zinc in acetic acid interestingly results in reduction of only one of the carbonyl groups to afford the isoindolone. There is thus obtained indoprofen (49). ... 

Improved polyurethane can he produced hy copolymerization. Block copolymers of polyurethanes connected with segments of isobutylenes exhibit high-temperature properties, hydrolytic stability, and barrier characteristics. The hard segments of polyurethane block polymers consist of 4RNHCOO)-n, where R usually contains an aromatic moiety. 

The radiation sensitivity of polymers and monomers is characterized by a G value the number of radicals formed per 100 e.v. (16 aJ) absorbed. Radiation sensitive groups include -COOH, C-halogen, -S02-, -NH2 and -C=C, Radiation resistant groups are aromatic rings. It appears that the presence of aromatic moieties also offers some degree of radiation protection to the polymer chain as a whole. 

Data are also available with a-acetylenic aliphatic sulphones, which involve only two steps i.e., saturation of the triple bond without subsequent cleavage of the Caliphalic—S bond, since it is not reactive. However, the introduction of an aromatic ring to the S02 group does not lead, contrary to what is observed with enones, to a potential shift toward less reducing potential values. Thus, the aromatic moiety introduced apparently does not bring any additional conjugation effect but even seems to decrease the activation of the unsaturated bond, as shown by data in Tables 6 and 7 where most of the potentials refer to the same saturated calomel electrode under similar experimental conditions. 

We postulate that the attack on both sides is accelerated by positive SOI (89a), but an unfavorable orbital interaction along the syn attack trajectory (89b) cancels the acceleration at the syn face [151] as the diene approaches the anhydride moiety (preferentially in endo fashion), unfavorable out-of-phase interaction (SOI) of the n lobes at Cj and of the diene with the tt lobes of the aromatic moiety of the dienophile occurs (89). The unexpected anti-selectivity stems from nnfavorable SOI on the syn side. 

Iron porphyrins display pronounced substrate preferences for alkene cyclopro-panation with EDA. In general, electron-rich terminal alkenes in conjunction with aromatic moiety or heteroatoms can efficiently undergo cyclopropanation with high catalyst turnover and selectivity. In contrast, 1,2-disubstituted alkenes cannot undergo cyclopropanation with diazoesters. Alkyl alkenes are poor substrates, giving cyclopropanated products in low yields. In both cases, the dimerization product diethyl maleate was obtained in high yield [53]. 

The SECSY spectrum of the coumarin presents cross-peaks for various coupled nuclei. These cross-peaks appear on diagonal lines that are parallel to one another. By reading the chemical shifts at such connected cross-peaks we arrive at the chemical shifts of the coupled nuclei. For instance, cross-peaks A and A exhibit connectivity between the vinylic C-4 and C-3 protons resonating at 8 7.8 and 6.2, respectively. The C-4 methine appears downfield due to its )3-disposition to the lactone carbonyl. Similarly, cross-peaks B and B show vicinal coupling between the C-5 and C-6 methine protons (8 7.6 and 7.1, respectively) of the aromatic moiety. The signals C and C represent the correlation between the oxygen-bearing C-11 (85.4) andC-12 (84.6) methine protons in the side chain. These interactions are presented around the structure. 

The most downfield cross-peaks, V-Y, are due to heteronuclear couplings of the aromadc or vinylic protons and carbons. For instance, cross-peak Y represents heteronuclear interaction between the C-1 vinylic proton (8 5.56) and a carbon resonating at 8 134.0 (C-1). The downfield cross-peaks, V and W, are due to the heteronuclear correlations of the ortho and meta protons (8 7.34 and 7.71) in the aromatic moiety with the carbons resonating at 8 128.3 and 126.9, respectively. The remaining cross-peak X is due to the one-bond correlation of the C-4 aromatic proton (8 7.42) with the C-4 carbon appearing at 8 131.4. The cross-peak U displays direct H/ C connectivity between the carbon at 8 77.9 (C-6) and C-6 methine proton (8 4.70). The crosspeak T is due to the one-bond heteronuclear correlation of carbon... 

Aromatic polyesters were efficiently synthesized from aromatic diacid divinyl esters. Lipase CA induced the polymerization of divinyl esters of isoph-thalic acid, terephthalic acid, and p-phenylene diacetic acid with glycols to give polyesters containing aromatic moiety in the main chain. The highest molecular weight (7.2 x 10 ) was attained from a combination of divinyl isophthalate and 1,10-decanediol. Enzymatic polymerization of divinyl esters and aromatic diols also afforded the aromatic polyesters. ... 

This model of the receptor-bound conformation of TIP is characterized by a clustered configuration of the three aromatic moieties with the Phe3 aromatic ring sandwiched between the Tyr1 and Tic2 aromatic rings. 

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