Studies on the Total Synthesis of Lactonamycin: Synthesis of the Fused Pentacyclic B–F Ring Unit



This paper describes an approach towards the total synthesis of lactonamycin with the elaboration of a key pentacyclic unit. Key steps include the synthesis of benzyl bromide 8 in eight steps and 23 % overall yield starting from 4-methoxyphenol; a high-yielding Suzuki coupling between boronic ester 9 and benzyl bromide 8; and a Lewis acid mediated, intramolecular Friedel–Crafts acylation to obtain the fused BCDEF ring core.