Syntheses of Papyracillic Acids: Application of the Tandem Chain Extension–Acylation Reaction

A synthetic approach to the papyracillic acid family of natural products has been developed. The spiroacetal core is rapidly assembled through an unprecedented zinc carbenoid-mediated tandem chain extension–acylation reaction. Subsequent functional group manipulation provided access to papyracillic acid B and 4-epi-papyracillic acid C. The successful preparation of these molecules resulted in the clarification of structural assignments of members of this family of natural products.