Acetyl group, donor

Acetyl-CoA is formed from CoA and acetate by the enzyme acetyl-CoA synthetase, an ADP-forming ligase. Phosphotrans-acetylase forms acetyl-CoA from CoA and acetyl-phosphate, which in turn is formed from acetate and ATP catalyzed by acetate kinase. Other enzymes that can form acetyl-CoA from CoA and other acetyl group donors include ATP citrate lyase and thiolase. Longer chain acyl-CoA thioesters are typically formed from CoA and a fatty acid catalyzed by ligases generally known as acyl-CoA synthetases. 

Thioesters and oxoesters are similar in their rates of nucleophilic acyl substitution, except with amine nucleophiles for which thioesters are much more reactive. Many biological reactions involve nucleophilic acyl substitutions referred to as acyl transfer reactions. The thioester acetyl coenzyme A is an acetyl group donor to alcohols, amines, and assorted other biological nucleophiles. 

The ability to promote /S elimination and the electron-donor capacity of the /3-metalloid substituents can be exploited in a very useful way in synthetic chemistry. Vinylstannanes and vinylsilanes react readily with electrophiles. The resulting intermediates then undergo elimination of the stannyl or silyl substituent, so that the net effect is replacement of the stannyl or silyl group by the electrophile. An example is the replacement of a trimethylsilyl substituent by an acetyl group by reaction with acetyl chloride. 

Electrochemical reduction of 5-acetyl-10-bromo-5/f-dibenz[ >,/]azepine in the presence of quinoxalinc as a moderator and diethyl malonate as a proton donor, effects rapid and quantitative hydrodebromination without loss of the acetyl group.183... 

Canavan s disease is the result of a deficiency of the enzyme that breaks down N-acetylaspartate, an important donor of acetyl groups for brain myelin synthesis 682... 

Two-carbon donor/product Malonyl CoA donor of one acetyl group Acetyl CoA product of 1 P-oxidation... 

An anomeric acetyl group can be removed selectively by treatment with hydrazine acetate or ammonium carbonate in DMF (Scheme 2.15c).46 The latter transformations are of great importance for the preparation of glycosyl donors such as anomeric trichloroacetimidates. 

In their initial report on the use of the 5-V-acetyl Neu5 Ac donors, Demchenko and Boons observed that the addition of the second acetyl group to the standard donor 6, resulting in the imide 7, increased the reactivity of the donor considerably on activation with. V-iodosuccinimide (NIS) and triflic acid (TfOH) at -40°C in acetonitrile (Scheme 5.3). The precise origins of this increased activity were not identified,... 

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