Polypropionates are key subunits in many macrolide- and ionophore-antibiotics.  They are characterized by a sequence of contiguous methyl- and hyrodoxy-bearing stereogenic centers.  For the past several years, our laboratory has focused its efforts in the development of a reiterative epoxide-based methodology for the synthesis of this challenging moiety.  The syn,anti,syn stereotetrad is present in many polypropionate natural products, such as the saliniketals, the ansamycin antibiotics rifamycin S and streptovaricin D, and the macrolide ionophores bafilomycin A1 and elaiophylin, among others.  A key precursor for this fragment is the syn,anti,trans-2-methyl-3,4-epoxy alcohol.  By using the Ireland-Claisen rearrangement, the synthesis of this important precursor can be obtained stereoselectively in gram quantities, using a minimum number of synthetic steps when compared to previous syntheses.  The Ireland-Claisen rearrangement has been adapted for our target precursors.  They have consistently produced high yields and excellent stereoselectivities increasing the usefulness and generality of our methodology.

General stereocontrolled strategy for the synthesis of <i>syn,anti,syn</i> stereotetrads using the Ireland-Claisen rearrangement

244th National Meeting (2012)

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General stereocontrolled strategy for the synthesis of syn,anti,syn stereotetrads using the Ireland-Claisen rearrangement