Brefeldin Brevicomin

As an alternative to baker s yeast, the use of plant tissues (e.g., from apple, carrot, cucumber, onion, or potato) has been suggested [112,113]. It remains unclear, however, whether endophytic microorganisms are involved in these reductions [114]. Heterocyclic ketones [111, 115-117] as well as many a-hydroxy ketones [96,118-121] have been the subject of yeast-mediated reductions. For the latter compounds very high ee values have been obtained, albeit the yields were moderate. Monobenylated (S)-l,n-diols have been prepared using highly diluted yeast suspensions, and ee values up to 95% could be achieved [122]. Yeast-mediated reductions of acyclic ketones were key steps in the total synthesis of the pheromone sulcatol [123], brefeldin A [124], and endo-brevicomin [125]. 

Finally, an elegant synthesis of brefeldin A started from 71 to afford (S)-72 with 99% e.e. [106], and a kinetic resolution by BY has been used for the synthesis of endo-brevicomin [107,108] (Fig. 21). Thus, reduction of racemic 75 under anaerobic conditions afforded via 76 a mixture of endo-11 (corresponds to a syn-selective reduction) and exo-78 [107]. 

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See also in sourсe #XX -- [ , ]

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