Structure determination fluoro compounds

The F-NMR spectrum was helpful in determining the structure of per-fluoro compound 54 (88JFC(38)303). 

The compound 1-fluoro-2,4-dinitrobenzene is exceedingly reactive toward nucleophilic aromatic substitution and was used in an imaginative way by Frederick Sanger (Section 27.11) in his determination of the structure of insulin. 

From a structural viewpoint, it is of interest to note that (35)-(37) as well as (32) all contain a 4-fluorophenyl moiety. This suggests that the 4-fluoro-phenyl group may play a role in determining the Class III electrophysiological profile of these compounds. 

The structure elucidation of 34 was based, in principle, on two facts color reactions and hydrolysis. Compound 34 does not react with ninhydrin (therefore, no primary amino group is present) but it does react with l-fluoro-2,4-dinitrobenzene. By exact determination of the absorption ratio E35O/E390 after the reaction with the latter reagent, Tait concluded that 34 contains a secondary amino group (50). Hydrolysis (6 N HC1, 110°C, 24 hr) of the so-called compound II afforded 2,3-dihydroxybenzoic acid and spermidine (50). The presence of two 2,3-dihydroxybenzoyl residues in 34 was demonstrated by its enzymatic (50) and chemical synthesis (51-54). 

The ability of PI synthetase to use 5-deoxy-5-fluoro-myo-inositol (4) as a substrate was confirmed by use of a radiolabeled compounds as shown in Figure 7. PI synthetase incorporated the analog into lipid in a time-dependent manner. The incorporation was absolutely dependent on the presence of CDP-diglyceride and was inhibited by the presence of myo-inositol (1) in the incubation mixture, as expected for PI synthetase. Chromatography of the reaction mixture revealed that a single radiolabeled product was formed with a mobility similar to, but distinct from, that of PI. Subsequent analysis has shown that the product is converted to a water-soluble form on mild alkaline hydrolysis and yields 5-deoxy-5-fluoro-myo-inositol (4) on treatment with phospholipase D, in agreement with the formation of phosphatidyl-5-deoxy-5-fluoro-myo-inositol as the product (data not shown). Determination of the absolute structure of these phospholipids awaits large-scale enzymatic synthesis, isolation of the product, and studies by mass spectrometry and NMR spectroscopy. 

New phenyl pyrroles are produced55 vhen certain analogues of tryptophan (dl-6-fluorotryptophan and dl-7-methyltrypto-phan) are added to pyrrolnitrin-producing cultures. The new compounds, it -fluoropyrrolnitrin and 3 > thyl-3 -dechloro-pyrrolnitrin, still possessed significant antifungal activity. The x-ray crystal structures of pyrrolnitrin and -fluoro-pyrrolnitrin have been determined.5° 57... 

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