Acetyl function

Interactions studies between some divalents metal ions and pectins from citms and sugar-beet revealed that the chemical structure of the latter, namely the presence of acetyl functions, induces differences of binding process whereas the scale of selectivity was not affected. Some further studies could be carried out on the correlation between the binding mode and the degree of acetylation. Lastly, pectins showed a clear scale of selectivity towards heavy metals with high capacities of binding which make them suitable to be used in waste-waters depollution. 

In other examples, also involving propargyl carbonates, the parent derivative 86 was first coupled with 87 - obtained by reaction of 5-octyne with the titanium diiso-propoxide - propene complex at -50 °C, providing the titanated vinylallene 88, which on hydrolysis furnished the vinylallenes 89 in good yield [29]. Carbonate 90 in the presence of a Pd° catalyst readily decarboxylated and yielded the allenylpalladium intermediate 91, which could be coupled with various vinyl derivatives to afford the vinylallenes 92. Since X represents a functional group (ester, acetyl), functionalized vinylallenes are available by this route [30]. 

Interesting cyano, polyoxyethylene, and O-acetyl functionalized N-acyl-amino acid derivatives can be obtained from functionalized olefins (Table 1). Diamidocarbonylation products may also be synthesized in moderate yields from terminal diolefins [13-15]. 

The medicinal chemistry of this period relied on simple modifications of the complex alkaloids. Deacetylation of 1 produced 4-deacetylvinblastine (98), a perfect substrate for these first experiments. Treatment if 1 with hydrogen chloride in anhydrous methanol gives 98 directly (91). Cleavage of the 4-acetyl function can also be effected by methanolysis, but during this period the acid-catalyzed methanolysis method was regarded as the preferred method. 

Treatment of the ammonium salt of 3,5-dinitro-1,2,4-triazole (113) with hydrazine hydrate leads to selective reduction of one of the nitro groups to yield 3-amino-5-nitro-1,2,4-triazole (ANTA) (114), a high performance explosive (calculated VOD 8460 m/s) possessing thermal stability (m.p. 238 °C) and an extremely low sensitivity to impact. ANTA (114) is also synthesized from the nitration of 3-acetyl-l,2,4-triazole with anhydrous nitric acid in acetic anhydride at subambient temperature followed by hydrolysis of the acetyl functionality. The ammonium salt of 3,5-dinitro-l,2,4-triazole (113) is itself a useful explosive which forms a eutectic with ammonium nitrate. ... 

At this point it is convenient to reiterate the major features and relationships normally encountered for polysaccharide structures. Each saccharide residue is normally linked through the reducing (hemi-acetyl) functional group (the anomeric position) to the hydroxy position of another residue. Each residue contains a number of hydroxy positions, but only one anomeric position. 

G. K. Hamer Yes, that peak comes from the N-acetyl function which is substituted for N-sulfate on the glucosamine. 

Acetylation of alkyl-substituted thienothiophenes (71)-(75) followed the same pattern, the incoming acetyl function entering an unsubstituted a-position. / -Substitution occurred only in the cases where available a-positions were blocked. Under vigorous reaction conditions, diacetylation has been reported to occur. Representative examples are set forth in Schemes 19-23 <76AHC(19)123). 

There is spectroscopic evidence for nickel-methyl complexes in CODH of anaerobic bacteria. Here the nickel center is linked to an Fe4S4 cubane cluster it is this, not Ni, which appears to act as the binding site for CO. In a subsequent step the methyl ligand is then transferred from Ni to the coordinated CO to generate the acetyl function of acetyl coenzyme A.28... 

Many derivatives of taxusin (3h, Fig. 2) [whose structure was confirmed in 1987 by X-ray diffraction (79)] possessing various hydroxylated or acetylated functional groups have been extracted from leaves, bark, or wood. In 1969, derivatives 3a-g were found in the heartwood of T. baccata (4). Another example of X-ray structural confirmation appeared in 1984 with that of one of the... 

The heterocyclic derivative (XXII), exhibits the basket form in the solid state, but variable temperature NMR data were not reported (367). The room temperature NMR data associated with the 6,11-protons are a function of the substituent on the N-atom, and the more complex spectrum with an acetyl functional group may imply a locking effect similar to that observed for the azepine derivative. 

SET Induced Reactions - Further studies on ring opening reactions of 1,2-diarylcyclopropanes have focused on compounds (83) bearing an acetyl functional group.All of the cyclopropane derivatives studied show efficient cis.trans isomerism with reasonable quantum efficiency. The isomerism reaction involves an acetophenone-like triplet state with lifetimes shorter than 1 ns. The formation of ring opened products also takes place but inefficiently to give a mixture of the two alkenes (84) and (85). A study of the electron-transfer-induced photochemical reactivity of the cyclopropane (86) has been reported in the co-sensitisation system (biphenyl/phenanthrene/DCA). ... 

---