Lipophilic groups

The third family (c. in Figure 9.1) less widespread, derived from the alkylphenols, offers as with the succinimides several possibilities of modification to the ratio of hydrophilic and lipophilic groups. Mannich s reaction of the alkyl-phenols also provides additives for lubricating oils. 

Carboxylate groups are hydrophilic ( water loving ) and tend to confer water sol ubility on species that contain them Long hydrocarbon chains are lipophilic ( fat loving ) and tend to associate with other hydrocarbon chains Sodium stearate is an example of an amphiphilic substance both hydrophilic and lipophilic groups occur within the same molecule... 

Cell membranes are lipophilic and designed to be barriers against large anionic molecules, although there is a natural mechanism for intercellular transport of anionic oligonucleotides. In order to enhance membrane transport, antisense oligonucleotides are frequentiy modified by covalent attachment of carrier molecules or lipophilic groups. 

This highly lipophilic group is cleaved with isoamyl nitrite in Pyr/AcOH. The use of a lipophilic 5 -phosphate protective group aids in reverse-phase HPLC purification of oligonucleotides. 

This lipophilic group, developed for 5 -phosphate protection in oligonucleotide synthesis, is removed with 80% AcOH in 1 h. The related trityloxyethylamino group has been used in a similar capacity for phosphate protection and is also cleaved with 80% AcOH. ... 

Other lipophilic groups possibly attached to the maleic acid anhydride are alkanolamides of fatty acids. In this case the variations could be chain length and/or saturation grade of the C chain, the type of alkanolamine (most common are isopropanolamine, monoethanolamine, and diglycolamine), or an etho-... 

Aliphatic phosphoric acid and phosphonic acid amides containing lipophilic groups were prepared and used as antimicrobial surfactants. For example, 100 g ethylmethanephosphonate chloride was added to a solution of 130 g dodecyl-amine and 72 g triethylamine in 500 ml anhydrous benzene at 20-30°C to give 192 g ethylmethanephosphonate N-dodecylamide [125]. 

Tarzia et al. [69, 70] have recently reported the FAAH inhibitory activity of a series of alkylcarbamic acid aryl esters. The starting point for their studies was the known serine hydrolase inhibitor carbamyl (51) that had no activity at FAAH. Replacement of the small methyl group of carbamyl (51) with more lipophilic groups and, in particular, bulky lipophilic groups resulted in increased affinity at FAAH (Table 6.6). Exploration of replacements of the naphthyl moiety revealed that replacement with a biphenyl group resulted in improved affinity and in particular, the 3-biphenylyl group proved effective... 

A range of different functional groups has been introduced into the V-position of the C3 side chain, as shown in Table 6.10. A number of different functionalities were shown to be tolerated in this position, with lipophilic groups such as methyl and dithiolane being preferred over polar groups such as ketones and alcohols. Ketone (118) had similar CBi receptor affinity to the unfunctionalised -heptyl compound (84), while alcohol (120) had lower affinity. The phenyl ketone (119) had lower CBi receptor affinity than the simple benzyl-substituted compound (116), but higher CB2 affinity, with about 12-fold selectivity for CB2 over CBi. 

Also deoxycholic acid (6) crystallizes in an inclusion lattice with channel-shaped cavities 13). Figure 3 shows that they are formed by facing molecules of deoxycholic acid, 4). This characteristic structural unit is a double layer of head-to-tail linked deoxycholic acid molecules at which specific H-bridges between hydroxy and carboxy groups are the decisive fact. The channels as such (e.g. in case of the orthorhombic crystal, see Fig. 3) are lined with lipophilic groups. Thus only van der Waals contacts are kept between the included guest molecules (also for polar molecules like acetone, Fig. 3) and the molecules of the channel wall. 

Mackellar, C., Graham, D., Will, D.W., Burgess, S., and Brown, T., Synthesis and physical properties of anti-HIV antisense oligonucleotides bearing terminal lipophilic groups, Nucleic Acid Research, 1992, 20, 3411-3417. 

Lipophilic group volume of surfactant molecule, v Decreases with increasing v... 

Length of lipophilic group, lc Increases with increasing lc... 

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