Acylation acetylation

Carriers of acyl/acetyl groups between mitochondria and cytosol Citrate (mitochondria to cytosol) Carnitine (cytosol to mitochondria)... 

D. Acylation Acetylation P almitoy lation Prenylation Histones Ras Ras Chapter 27 Section D,3 Chapter 22... 

Toppings are spray-dried emulsions made from sodium caseinate, vegetable fat such as palm kernel or coconut fat, and emulsifiers with low polarity, such as acylated (acetylated or lactylated) monoglycerides or propylene glycerol monostearate. 

Decomposition of alkylbenzene Ph-Me, Ph-Et, Ph- Pr Friedel-Crafts acylation acetylation, benzoylation, and so on Isomerization of paraffin open-chain C1-C7, cyclic Cs-Cn Esterification -> AcOH + MeOH, EtOH, and so on CgOH + phthalic acid, and so on Cationic polymerization Me, Et, Bu vinyl ether Oligomerization 3-pinene, 1-octene, 1-decene Others -> aldol condensation, and so on... 

Another methodology applied to the monosubstitution of diols is the use of copper complexation of dianions. The dianion is first formed by reaction of a diol with two equivalents of NaH. The copper complex is then formed by addition of a copper salt. Reaction of the copper complex with various electrophiles (alkyl halides, acyl chlorides) then gives the selectively protected products. As with the phase-transfer technique, very little disubstitution is observed. However, as illustrated in Scheme 3.16, the regioselectivity is reversed (i.e., 4,6-diols give mainly 4-substitution and 2,3-diols give mainly 3-substitution). Using this technique, both alkylations (benzylation, allylation) and acylations (acetylation, benzoylation, pivaloylation) have been carried out. As usual, the degree of selectivity depends on reaction conditions and structural factors [44]. 

Acid chlorides convert l-methylbenzimidazol-2-yl-silanes and -stannanes into 2-acylbenzimidazoles. The reaction also works with imidazoles, with the stannanes being more reactive than the silanes. The mechanism is believed to involve initial 7V-acylation, then loss of the silicon or tin substituent to give a zwitterion, and finally N -> C-migration of the acyl group. As in Regel acylation, acetyl chloride will not induce the reaction <83JHC1oii>. 

Keywords Friedel-Crafts acylation, acetyl anhydride... 

Acyl halides bearing a-hydrogen atoms, and acetyl chloride in particular, have limited stability in the presence of strong Lewis acids. Elimination of proton from the acylium ion leads to the ketene. This intermediate undergoes ready Friedel-Crafts acylation, acetyl chloride eventually forming the diacetylace-tylium ion, ° which is a poor acylating agent. For this reason, excessive reaction temperatures and times should be avoided in Friedel-Crafts acetylations. 

A -methoxymethyl-amines or-amides A -acetyloxymethyl-amines or -amides or A/, iV-dimethylfonnamide acetals, all react with phosphorus(III) esters in non-classical Michaelis-Arbuzov fashion. From these and similar reactions, quaternary salts of the type 186 have been isolated. The A-methylated dervative may be preformed or produced in situ in mixtures containing amide, formaldehyde and phosphite ester. The products of the reactions are A-acylated (acetyl, benzoyl, phthaloyl, pyridinecarbonyl or benzyloxycarbonyl) when derived from amides, or A,A-dialkyl derivatives from hydroxy (or methoxy)methylamines the use of Me2NCH(OMe)2 leads to dimethylaminomethyl-enebisphosphonic esters. Ivanov and coworkers have made a detailed study of the reactions which occur between phosphorus(III) amides Et2NPYZ and the substrates, RCONHOAc (Scheme 16). The reagent can attack the substrate by virtue of the nucle-... 

Acetylation and acylation. Acetylation of e-amino groups on conserved Lys residues in the N-terminal domains of the core histones, H2A, H2B, H3 and H4, is the most common post-translational modification of chromatin. Acetylation substantially weakens the constraints on DNA imposed by the core histones and provides molecular mechanism by which DNA becomes accessible to transacting factors while maintaining a nucleosome architecture (Wade et al, 1997). Histone acetylation is reversible and is controlled by a group of acetyltransferases and deacetylases. The balance between histone acetyltransferases and deacetylases determines the accessibility of the chromatin to the transcriptional machinery. Thus the acetylation status of histones is a key determinant of transcriptional activity. Transcription activators are often associated with histone acetyltransferases and repressors can interact with histone deacetylases (Ng and Bird, 2000). 

Exclusive alkylation of normally unfavored positions in (po/y-N)-heterocyclics can be achieved by using acyl (acetyl, benzoyl, carbethoxy) as N-protective groups. - E Trimethyloxonium fiuoroborate in nitromethane dropped rapidly under anhydrous conditions into a cooled soln. of l-acetyl-1,2,4-triazole in the same solvent, methanol added to hydrolyze the acyl cation to the protonated salt, and the aq. soln. of the latter neutralized with Na-carbonate -> 4-methyl-l,2,4-triazole. Y 88%. F. e., also alkylation with carboxonium salts, s. R. A. Olofson and R. V. Kendall, J. Org. Chem. 55, 2246 (1970). 

Typical derivatives of the first type are the various esters (Me, Et, Pr, iso-Pi, Bu, wo-Bu, cc-Bu, Am, tio-Am, etc.) of A -acyl (acetyl, TEA, PFP, HFB, etc.) amino acids. The butyl esters of iV-TFA amino acids owing to the frequency of their use even have a special abbreviation TAB derivatives. The two-stage process includes the esterification of amino acids by an excess of the corresponding alcohol in the presence of HCl and, after the evaporation of volatile compounds, the treatment of the non-volatile hydrochlorides of alkyl esters by acylating reagents (Fig. 1). 

R = alkyl, aryl Acyl = acetyl, chloroacetyl, benzyloxycarbonyl... 

Friedel-Crafts Acylation. Acetylation and benzoylation of aromatics have been performed in ionic liquids such as [BMIM]-[BF4] by using Cu(OTf)2 as catalyst. Under these conditions, benzoylation of activated aromatics such as anisole (eq 16) is reported to be quantitative and exhibits high para-selectivity (orthapara = 4 96). 

Effect of acylation. Formation of lysinoalanine from lysine re-quires the participation of an e-amino group of a lysine side chain. Therefore, it was expected that protection of amino groups by acylation (acetylation, succinylation, etc.), would reduce ly-sinoalanine formation under alkaline conditions, if the protective group (s) survived the treatment. Results in Tables strikingly demonstrate that acetylation of wheat gluten prevents lysinoala-nine formation. 

Reaction 3 shows the transfer of an acyl (acetyl) group to CoA. In the presence of Pi and phosphotransacetylase, the acyl group would accumulate as acetyl phosphate. The transacetylase reaction of lipoic acid has been determined by employing the reverse of the phosphotransacetylase reaction, mentioned above, and reaction 3 of Fig. 4. In the presence of catalytic amounts of CoA, lipoic transacetylase activity can be demonstrated by measuring the accumulation of a heat-stable hydroxamic acid derived from the acyl-Iipoate or by measuring the disappearance of —SH groups. 

C-Acetyl... s. Methyl ketones Acetylacetonates s. Metal acetoacetonates Acetylation (s. a. Acylation) Acetyl diloride as reagent 29, 993... 

The synthesis of l-0-alkyl-(Me, Bn, Oct, dodecyl etc.) and 1-O-acyl (acetyl or stearoyl)-myo-inositol 3,4,S-trisphosphate as analogues of phosphatidyl myoinositol 3,4,5-trisphosphate and of myo-inositol 4,5,6-trisphosphate as an analogue of myo-inositol l,4,5-trisphosphate have been reported. 

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