Divergent synthesis of four isomers of 6,7-dihydroxy-3,7-dimethyloct-2-enoic acid,esters and evaluation for the antifungal activity

The four isomers of 6,7-dihydroxy-3,7-dimethyloct-2-enoic acid 2 were synthesized via the selective direct Sharpless asymmetry dihydroxylation of geraniol as the key step in 35.0%-48.0% overall yields with91.9%-97.7% ee values for esters 4 and 31,3%-36.4% overall yields with 90.3-97.5% ee values for acids 2 using cis-and trans-geraniol as raw materials. Their structures were characterized by;H,;C NMR and HR-ESI-MS data. The in vivo bioassay results showed that the chiral acid（Z, S）-2 was a good lead compound with 80%-100% inhibitory rates against P. cubensis, E. graminis, P. sorghi and C. gloeosporioides at the concentration of 400 μg/mL.

The four isomers of 6,7-dihydroxy-3,7-dimethyloct-2-enoic acid 2 were synthesized via the selective direct Sharpless asymmetry dihydroxylation of geraniol as the key step in 35.0%-48.0% overall yields with91.9%-97.7% ee values for esters 4 and 31,3%-36.4% overall yields with 90.3-97.5% ee values for acids 2 using cis-and trans-geraniol as raw materials. Their structures were characterized by ~1H, ^(13)C NMR and HR-ESI-MS data. The in vivo bioassay results showed that the chiral acid(Z, S)-2 was a good lead compound with 80%-100% inhibitory rates against P. cubensis, E. graminis, P. sorghi and C. gloeosporioides at the concentration of 400 μg/mL.