Stereoselective hydrogenation of methylcyclohex-2-ene-1,4-diols used in the synthesis of ampelomins and deoxy-carbasugars

Achievements, Challenges, and Scope of Thirty Years of Work on the Biotransformation of Arenes and Their Synthetic Applications

“…The enantioselective sequence, developed to obtain the desired ampelomins, involved starting from a precursor of known absolute configuration, compound 127. [117] In order to synthesize the ampelomins B, epi-B, D, and E, different approaches were designed based on changing the order of some reactions in the synthetic sequences from an advanced common intermediate, 127 (Scheme 34) which could be prepared from key enantiopure cis-diol 1 available by dioxygenase-mediated oxidation of toluene, using E. coli JM109 (pDTG601) as the whole-cell biocatalytic system, as it was previously presented. [117] Key steps of the preparation include a stereoselective homogeneous hydrogenation, a Mitsunobu reaction, and a regio-and stereoselective nucleophilic opening of an epoxide, which allowed the synthesis of either of the cited ampelomins merely by changing the order of events from the common precursor 127, (Scheme 34).…”

“…[117] In order to synthesize the ampelomins B, epi-B, D, and E, different approaches were designed based on changing the order of some reactions in the synthetic sequences from an advanced common intermediate, 127 (Scheme 34) which could be prepared from key enantiopure cis-diol 1 available by dioxygenase-mediated oxidation of toluene, using E. coli JM109 (pDTG601) as the whole-cell biocatalytic system, as it was previously presented. [117] Key steps of the preparation include a stereoselective homogeneous hydrogenation, a Mitsunobu reaction, and a regio-and stereoselective nucleophilic opening of an epoxide, which allowed the synthesis of either of the cited ampelomins merely by changing the order of events from the common precursor 127, (Scheme 34). With these guidelines in mind, the ampelomins were synthesized from toluene in 20% overall yield for ampelomin B, 45% overall yield for epiampelomin B, 40% overall yield for ampelomin E, and 14% overall yield for ampelomin D (Scheme 34).…”

“…The enantioselective sequence, developed to obtain the desired ampelomins, involved starting from a precursor of known absolute configuration, compound 127 [117] …”