Total Synthesis of the Carboxylic Acid lonophore Antibiotic CP-61,405 (Routiennocin): Preparation of the Inherent Spiroketal Unit via a Reverse Coupling Process

Abstract

π-Allyltricarbonyliron lactone complexes were used in the preparation of a 6-substituted 5-methyl-2-phenylsulphonylpyran 3 which when coupled with 6-iodo-1,3-O-isopropylidenehexane-1,3-diol (4) gave the inherent spiroketal fragment (2,8-disubstituted 1,7-dioxaspiro[5.5]undecane 2) of the ionophore antibiotic CP-61,405 (Routiennocin) 1.