2-Benzylmalic acid

Isobutylmalic acid (18) and (— )-2-benzylmalic acid (19), the constituent acids of cornucervine and phalaenopsine La, respectively, have now been shown to have the / -configuration. This was established by a partial asymmetric synthesis of the enantiomers of these acids and comparison of the c.d. spectra of their molybdate complexes with that of the molybdate complex of (-f )-citramalic acid (20) of known S-configuration. 

Comucervine and the phalaenopsines (Table 3 C, D, and F) give (—)-2-isobutylmalic acid (76) and (—)-2-benzylmalic acid (77) on alkaline hydrolysis. Both acids have been assigned the R absolute configuration by Brand ANGE et al. (55) by partial asymmetric synthesis of the enantiomers of both acids and comparison of their circular dichroism spectra with those of (S)-(+)-citromalic acid (78). 

Migaud ME, JC Chee-Sandford, JM Tiedje, JW Frost (1996) Benzylfumaric, benzylmaleic, and Z- and -phenylitaconic acids synthesis, characterization, and correlation with a metabolite generated by Azoarcus tolulyticus Tol-4 during anaerobic toluene degradation. Appl Environ Microbiol 62 974-978. 

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