- Biosynthesis of porphyrins and related macrocycles. Part 52.1'2 Synthesis of 1-SH11-4Hjporphobilinogen and the (11R)enantiomer for stereochemical studies on hydroxymethylbilane synthase (porphobilinogen deaminase)
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A synthetic route is devised for the synthesis of (115)-[11-2H,]porphobilinogen la and of the (1 lβ)-enantiomer Ib. Their absolute configurations and enantiomeric purity are established by degradation to a derivative of [2-2H,]glycine of known stereochemistry. Methods are then developed, based on the synthesis of chiral imidate esters, for determination of the configuration of [2H1]-labelled aminomethylpyrroles by converting them into [2H,]-labelled amidines followed by analysis using 'H-NMR. The labelled samples of PEG la and Ib serve as substrates for hydroxymethylbilane synthase and the products are trapped as [2H1]-labelIed aminomethylbilanes 7c and 7d. Their configurations are determined by the NMR assay to demonstrate that as PBG 1 is enzymically converted into the aminomethylbilane 7, there is overall retention of configuration at the aminomethyl carbon. The Royal Society of Chemistry 1999.
- Neidhart, Werner L.,Anderson, Paul C.,Hart, Graham J.,Battersby, Alan R.
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p. 2677 - 2689
(2007/10/03)
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- Chiral Lactols, II. Racemate Separation and Enantioselective Acetalisation with the 2,3,3a,4,5,6,7,7a-Octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl Protective Group
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A simple method for the resolution of the chiral alcohols, cyanohydrins, thiols and amines rac-2a - f by the reaction with the chiral protective group 1a ( or 1b, respectively) is described.The diastereomeric derivatives 3a - f and 4a - f are separated by column chromatography or crystallisation.Subsequent methanolysis or hydrolysis, respectively, yields the enantiomers and the recovered protective group.With rac-2a - c preferential acetalisation of the (R)-enantiomers was observed.This phenomenon was investigated by modification of the protective group.Considerations on conformations of 3a point to an important role of the anomeric and exo-anomeric effect in this enantioselective reaction.
- Noe, Christian R.
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p. 1591 - 1606
(2007/10/02)
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