Menthyl succinate

DL-menthyl succinate L - specific L-menthol + D-menthyl succinate... 

The process uses cells of Rhodotorula minuta entrapped in polyurethane. These cells selectively hydrolyse the L-ester. The remaining D-menthyl succinate is then hydrolysed and the 15-menthol racemised via D-menthone and then recycled. We have represented this process in Figure 9.9. 

Chiral 1,2-cycloalkanedicarboxylic acids.1 This ring system can be obtained by coupling 1,co-dihalides or -ditosylates with the dienolate of d- or /-menthyl succinate (1). The dienolate generated with lithium 2,2,6,6-tetramethylpiperidide is mainly the (E,E)-isomer, whereas deprotonation with LDA and HMPT generates mainly the (Z,Z)-isomer. Thus reaction of 1 (R = /-menthyl) with LiTMP in THF at -78° with CH2BrCl results in (S,S)-( - )-dimenthyl cyclopropane-frww-1,2-dicarboxylate (2) in 58% chemical yield and 99% de. A similar reaction of 1, R = d-menthyl, results in (R,R)-2 in 60% yield and 80% de. 

FIGURE 19.62 Asymmetric hydrolysis of racemic menthyl succinate (137b- and 137b -succinates) to obtain pure (-)-menthol (137b). (Modi ed from Yamaguchi, Y. et al., J. Agric. Chem. Soc. Jpn., 51, 411,1977.)... 

Omata, T., N. Iwamoto, T. Kimura, A. Tanaka, S. Fukui, 1981. Stereoselective hydrolysis of <7/-menthyl succinate by gei-entrapped Rhodotorula minuta var. texensis cells in organic solvent. Appl. Microbiol. BiotechnoL, 11 119-204. 

Omata, T., Stereoselective hydrolysis of D,L menthyl succinate by gel-entrapped Rhodotorula minuta var. texensis in organic solvent, Ap/>/. Microbiol. Biotechnol, 11, p. 199, 1981. 

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