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Tertiary basic functionality

The structures of some of the better known plant alkaloids are shown in Figure 23-1. You will recognize some of them by name even if you have never seen their structures before. Many of the alkaloids are polycyclic structures and have other functional groups in addition to basic nitrogen. You will see that the nitrogens of alkaloids frequently are tertiary amine functions. [Pg.1098]

It is remarkable that, for histamine, very few compounds of plant origin have been found to have JI (or H2, H3, H4) -blocking properties (Fig. 18.17). a-Mangostin [28] is an example, although remarkably this compound (a competitive H, antagonist) does not carry a basic function. A basic tertiary amino group is also absent in cicletanide, an intriguing compound that has a chiral center and in which the antihistaminic activity resides in the levo isomer (Fig. 18.17). Rocastine and temelastine are two other antihistaminic compounds with unusual structures (Fig. 18.12). [Pg.415]

WBA = weak basic anion exchanger containing tertiary amine functions SAC = strong acidic cation exchanger containing sulfonic functions WAC = weak acidic cation exchanger containing carboxylic functions dso = sizt of 50% micro- or macropores na = no data presented S=specific surface area fFo = specific pore volume. [Pg.356]

Four pharmacophores have been identified in CCR5 antagonists 6, namely, a tertiary basic amine, two tail hydrophobes one of which tolerates some polarity, and a (hetero)aryl head (Figure 3.5). In a series of these inhibitors, lipid permeability was very low and strategies to remove the amide function in tail hydrophobe 1 were progressed. Replacement of the secondary amide with a piperidine 7 or azetidine 8 moiety led to the discovery of compounds with increased intrinsic lipoidal membrane permeability and overall an improved in vivo pharmacokinetic profile [7]. [Pg.34]

Early classical extraction methods for PAs were applied without much consideration of the range of chemical structures of the alkaloids and in particular were not optimized to obtain the maximum yields of both the tertiary and oxide forms. In fact few publications even today describe the recovery achieved with the extraction procedure used. PAs have either a reduced tertiary nitrogen atom with a characteristic basic function or an oxidized form (PANO). Both forms have little solubility in non-polar solvents such as hexane and are best extracted with polar solvents such as methanol or with aqueous dilute acid. These solvents dissolve both the PAs and the PANOs with relative ease. [Pg.1052]

If basic functional groups are introduced, the resin can exchange anions rather than cations. Strong anion exchangers are prepared with a tertiary simine, yielding a strongly basic... [Pg.389]

Rationale behind derivatization relates to the chemistry of the analyzed compounds (AA and AC). Both have either a basic functional group (amine for the AA, tertiary amine for the carnitines—free or acylated forms) or an acidic group. Since the yield of the ESI process is related to the overall proton affinity of the molecule itself, by neutralizing the acidity of the carboxylic moiety with esterification, the resulting proton affinity increases and therefore sensitivity is enhanced. [Pg.357]

The catalytic properties of the natural cinchona alkaloids are related to the presence of a basic tertiary amine function (of the quinucUdtne ring) and the hydrogen bonding properties of the hydroxyl group of the C9 site. In addition, the conformational behavior of these molecules is essential for their reactivily as bifunctional catalysts [12]. Four low-energy conformers were identified with NMR spectroscopy and computational techniques and shown to be interrelated by rotations about the C4 -C9 and C9-C8 bonds (Figure 6.4) [13,14]. [Pg.121]


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See also in sourсe #XX -- [ Pg.324 ]




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