Configuration of malic acid

The absolute configuration of the major isomers of spirolactone 102 and amide 103 was ISySRyl R, based on the known configuration of malic acid and determination of the relative configuration by an X-ray structure analysis of amide 103 [62]. 

The foundation for the configuration of these amino acids will be obtained if a-amino-y8-chloropropionic acid can be converted into aspartic acid, the configuration of which is known from its relationship to malic acid, (d-aspartic acid is converted into d-malic acid by nitrous acid.) The configuration of malic acid can be referred to that of tartaric acid and thence to d-glucose. 

Aspartate ammonia-lyase was also used to provide (25,3/ )-[3-2H]aspartic acid, and the latter was converted (NH2 - Br -> H) to (2R)-[2-2H]succinic acid [99]. Since the stereochemical assignment for aspartate ammonia-lyase also relies on the configuration of malic acid, this synthesis does not provide an unambiguous verification of the succinate configuration. 

Fig. 4. Illustration of the sterio configuration of malic acids arising by hydration of fumaric acid.

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See also in sourсe #XX -- [ , , ]

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