Total synthesis of the antiparasitic agent avermectin B1a

Article abstract of DOI:10.1021/ja00112a006

The synthesis of avermectin B_1a has been completed by a route that assembles the aglycon from three subunits consisting of the hexahydrobenzofuran moiety (A), the spiroketal segment (B), and the acyclic portion (C) comprising C9-C15. Connection is made in a B + C → (B -C) + A sequence, and the synthesis is concluded by attachment to the aglycon of the L-oleandrosyl-L-oleandrose disaccharide via the pyridylthio glycoside.