A New Method for the Preparation of Non‐Terminal Alkynes: Application to the Total Syntheses of Tulearin A and C. Issue 1 (3rd November 2014)

• Record Type: Journal Article
• Authors: Lehr, Konrad; Schulthoff, Saskia; Ueda, Yoshihiro; Mariz, Ronaldo; Leseurre, Lucie; Gabor, Barbara; Fürstner, Alois
• Is Part Of: Chemistry. Volume 21:Issue 1(2015)
• Page Start: 219
• Page End: 227
• Publication Date: 2014-11-03
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201404873
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Lactones are known to react with the reagent generated in situ from CCl₄ and PPh₃ in a Wittig‐type fashion to give <italic>gem</italic>‐dichloro‐olefin derivatives. Such compounds are now shown to undergo reductive alkylation on treatment with organolithium reagents RLi to furnish acetylene derivatives bearing the substituent R at their termini (R=Me, <italic>n</italic>‐, <italic>sec</italic>‐, <italic>tert</italic>‐alkyl, silyl); the reaction can be catalyzed with either Cu(acac)₂ or Fe(acac)₃/1, 2‐diaminobenzene. Two alkynol derivatives prepared in this way from readily accessible lactone precursors served as the key building blocks for the total syntheses of the cytotoxic marine macrolides tulearin A (<bold>1</bold>) and C (<bold>2</bold>). The assembly of these fragile targets hinged upon ring closing alkyne metathesis (RCAM) followed by a formal <italic>trans</italic>‐reduction of the resulting cycloalkynes via <italic>trans</italic>‐hydrosilylation/protodesilylation.</p> </abstract>