Acetylation exhaustive

In addition, it was clear that the presented scheme does not exhaust all the possible paths of anomalous chlorination. Thus, 4-acetyl-l,3,5-trimethylpyrazole with 4-5 moles of phosphorus pentachloride gave mainly 4-Q ,/3-dichlorovinyl-5-chloromethyl-l,3-dimethylpyrazole, and its precursor (according to GLC data) was the dichloride. It could be possible that in the case of 4-chlorovinyl derivatives of pyrazole the chlorination at the p position is facilitated by the electron-donating characteristics of the 4-pyrazolyl radical (86TH1). 

Reductive opening of the oxirane ring of 193 with lithium aluminum hydride, and acetylation, provided compound 194. Epoxidation of 194 with mCPB A gave the epoxide 195. Opening of the oxirane ring with acetate ions, followed by acetylation, gave the tetraacetate 196, or, by exhaustive acetylation with acetic anhydride-DMAP, the pentaacetate 189. Compounds 196 and 189 were readily transformed into 190 by hydrolysis. " ... 

That molecule is then subjected to the standard carbonyl reduction, Birch reaction, oxidation, ethynylation and, finally, hydrolysis sequence (see 50 to 53). Hydrolysis of the enol ether under more strenuous conditions than was employed with 53 gives the conjugated ketone 65. The carbonyl group is then reduced to afford the corresponding 3p-alcohol (66). Exhaustive acetylation affords the potent oral progestin methynodiol diacetate (67). 

Exhaustive examples have demonstrated that 1,3-disubstituted bicyclo[l.l.l]pentanes can be conveniently prepared by radical addition to [l.l.l]propellane.39-43,47 Of particular interest is the peroxide-catalyzed [( -BuO)2, hv] addition of acetaldehyde to [1.1, l]propellane, which gives the 2 1 adduct l-acetyl-3-(1-hydroxyethyl)bicyclo[l,l.l]pentane (25) in a transformation pre-... 

When the blood glucose level falls and the liver s glycogen reserves are also exhausted, the liver still has the capacity to synthesize glucose via gluconeogenesis from amino acids that are supplied from protein breakdown. Under starvation conditions the liver forms increasing amounts of ketone bodies (see fig. 18.7). This is due to elevated concentrations of acetyl-CoA, which favor the formation of ketone bodies. The ketone bodies are secreted and used as a source of energy by other tissues, especially those tissues like the brain that cannot catabolize fatty acids directly. 

Functionalization of 1 by cu-glycol formation, performed with osmium tetroxide, followed by hydrogenolysis of the N—O bond and exhaustive acetylation of the hydroxy groups, allows ( + )-V-phenylamino sugars derivatives to be obtained82. 

A trisaccharide isolated from milk was completely hydrolyzed by /3-galactosidase to galactose and glucose in a 2 1 ratio. Reduction of the original trisaccharide with NaBH<, followed by exhaustive methylation, acid hydrolysis, then another NaBH< reduction step, and finally acetylation with acetic anhydride yielded three products (a) 2,3,4,6-tetramethyl-1,5-diacetyl-galactitol, (b) 2,3,4-trimethyl-l,5,6-triacetylgalactitol, and (c) 1,2,3,5,6-... 

The selection of derivatization methods for amides and imides is not as great as for other classes of amino compounds. The active hydrogen atom in the structural fragments —CO — NH— or SO2 — NH— is highly acidic and, hence, sometimes recommended TMS, acetyl, or TEA derivatives of these compounds are unstable during hydrolysis. The best derivatization method is their exhaustive alkylation (preferably methylation), because permethylated amides and imides are volatile enough for their GC analysis. This general statement can be illustrated by retention data... 

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