Formal Total Synthesis of (−)-Isolaurallene and Structure Determination of (+)-4-<i>epi</i>-Isolaurallene via Stereodivergent Intramolecular Amide Enolate Alkylation

Described herein are the formal total syntheses of (-)-isolaurallene (<b>1</b>) and structure determination of newly isolated (+)-4-<i>epi</i>-isolaurallene (<b>2</b>) via a highly stereodivergent intramolecular amide enolate alkylation (IAEA) strategy. Highly stereoselective constructions of α,α'-<i>trans</i>-THF <b>3</b> and α,α'-<i>cis</i>-THF <b>4</b> were accomplished by subjecting common intermediate <b>5</b> to non-chelate-controlled and chelate-controlled IAEA, respectively. The former protocol greatly improves the moderate stereoselectivity previously observed in constructing α,α'-<i>trans</i>-THF rings via intramolecular nitrile anion alkylation (INAA).