Carvone derivatives hydrogenation

The selectivity of the epoxidation, in conjunction with the availability of optically active terpenes from natural sources, has resulted in the application of terpene epoxides as starting materials for the synthesis of several natural products. Both enantiomers of carvone, (10) and (ent-l0), have been used for the synthesis of methyl trans- and c/.v-chrysanthemates 15 and ent-15. i+Hsy Carvone (10) was converted into hydrochlorinated compound 13 and the methylated derivative 11, which were selectively epoxidized with alkaline hydrogen peroxide, and further converted into methyl trum-chrysanthcmate 15. The same route led from (— )-(/ )-carvone ent-10) to m-chrysanthemate ent-1543 ent-13 was converted to ( + )-a-3,4-epoxycaran-2-one 1644. 

Biotransformation by the recombinant reductase and the transformed Escherichia coli cells were examined with pulegone, carvone, and verbenone as substrates (Figure 19.126). The recombinant reductase catalyzed the hydrogenation of the exocyclic C = C double bond of pulegone (119) to give menthone derivatives (Watanabe et al., 2007) (Tables 19.12 and 19.13). 

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