Polyacylations

Product complex 7 as well as the free product 3 are much less reactive towards further electrophilic substitution as is the starting material thus the formation of polyacylated products is not observed. If the starting material bears one or more non-deactivating substituents, the direction of acylation can be predicted by the general rules for aromatic substitution. 

Because polyacylation does not occur (cf. p.145), it is often preferable to prepare alkyl-benzenes by acylation, followed by Clemmensen or other reduction, rather than by direct alkylation ... 

Pereda-Miranda R, Kaatz GW, Gibbons S (2006) Polyacylated Oligosaccharides from Medicinal Mexican Morning Glory Species as Antibacterials and Inhibitors of Multidrug Resistance in Staphylococcus aureus. J Nat Prod 69 406... 

This experimentally simple one-pot operation addresses the issue of polyacylation without resorting to a large excess of hydroxylamine or to protection. 

Friedel-Craft acylation. Neither is polyacylation, because the first acyl group serves to deactivate the ring to further attack. 

Yoshida, K. et al., A UV-B resistant polyacylated anthocyanin, FIBA, from blue petals of morning glory. Tetrahedron Lett., 44, 7875, 2003. 

Honda, T. and Saito, N., Recent progress in the chemistry of polyacylated anthocyanins as flower color pigments. Heterocycles, 56, 633, 2002. 

It is known that polyacylated anthocyanins are very stable in neutral or weakly acidic aqueous solutions, whereas simple anthocyanins are quickly decolorized by hydration at the 2-position of the anthocyanidin nucleus. The shift to blue colors and increased anthocyanin stability are in many cases simply achieved by intramolecular copigmentation involving... 

Clitoria ternatea contain mainly ternatins (polyacylated delphinidin 3,3, 5 -triglucosides) and preternatins. The change in flower color from blue to mauve in this species is caused by lack of (polyacylated) glucosyl substitutions at both the 3 - and 5 -positions of the ternatins. 

Nearly 35 different anthocyanins have been reported to occur in one or more species in the family Ranunculaceae (Figure 10.15), and 24 of these have been reported after 1992 as novel compounds. Flowers of species in the genera Delphinium (blue), ° Consolida (blue-violet), and Aconitum (purplish-blue) " contain similar anthocyanins with polyacyl substitution based on -hydroxybenzoylglucose residues at the 7-hydroxyl of delphinidin, in addition to a more simple glycosyl moiety at the 3-position. Red flowers of Delphinium hybridum share a similar 3,7-disubstitution pattern based on pelargonidin instead of delphinidin. 

Yoshikawa, M. et al.. New flavonol oligoglycosides and polyacylated sucroses with inhibitory effects on aldose reductase and platelet aggregation from flowers of Prunus mume, J. Nat. Prod., 65, 1151, 2002. 

Regioselective alcoholysis of polyacylated steroids catalyzed by Candida rugosa lipase suspended in acetonitrile or di-isopropyl ether in the presence of octanol has also been reported [88]. Similarly, the alcoholysis of peracetylated chalcones, acetophenones, and benzopyranones has been reported [89]. 

A synthetic route was established for the preparation of an (),N-polyacyl glucosamine 3(l-6)disaccha-ride 1,4 -diphosphate which corresponds to the proposed structure of Salmonella-type lipid A. Many structural analogs were prepared in order to elucidate the true structural requirements for the biological activities of lipid A. 

Figure 9. Analysis of anions and cations in river water using tartaric acid/18-crown-6/methanol-water eluent with a carboxylated polyacylate stationary phase in the protonated form. Ions 1) sulfate 2) chloride 3) nitrate 4) eluent dip 5) unknown 6) sodium 7) ammonium 8) potassium 9) magnesium 10) calcium (from ref. 80)...

Fig. 12.6 A transfer-NOE derived space-fill model of the polymyxin B (PMB) -lipid A complex. Bidendate ionic H-bonds between pairs of the y-amino groups of Dab residues of PMB and the phosphates of lipid A, as well as hydrophobic interactions between the methyloctanoate group of PMB and the polyacyl domain of lipid A stabilize the interactions...

Besides N-acylated enamines, enamides containing a functional group in the carbon skeleton are obtained in the acid-catalyzed reactions of carbonyl compounds with nitriles. Some of them were shown in equations 18, 28, 31, 33, 38, 58, 59, 63, 65, 75 and 87 and they are mainly the polyacylated enamines (e.g. /Lacylaminovinyl ketones 79, 87, 93, 200, 207 and 278). Most of them are intermediates in the synthesis of oxygen and nitrogen containing heterocycles or products of further conversions of the latter. 

Flavonoids acylated with hydroxycinnamic acids show a UV spectrum of the flavonoid overlapped with that of the acid, this last being the main one. They are characterized by a maximum with a high absorption 330nm (310-335 nm), and eventually can show a small maximum that coincides with the flavonoid band II ( 255-268 nm) and a shoulder at higher wavelengths that reflects the flavonoid Band I (Vallejo et ah, 2004). In polyacylated flavoneglycosides, in which two or even three hydroxycinnamate molecules are attached to the flavonoid... 

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