Total Synthesis of Laingolide B Stereoisomers and Assignment of Absolute Configuration

Total synthesis of (−)-(2R,9S)- and (+)-(2S,9S)-stereoisomers of laingolide B has been accomplished by using sequential ring-closing metathesis (RCM) and alkene isomerization to construct the macrocyclic trans-N-methyl enamide moiety. The Myers alkylation was used to secure the C2 stereochemistry of the two RCM precursors from a common (9S)-C3–C9 alkyl iodide. The absolute configuration of laingolide B has been assigned as (2S,9R) by comparison of the optical rotation data.