Stereoselective synthesis of exocyclic allenes by double hydride reduction of 3-alkynyl-2-cycloalkenones

Matthew A. Gubbels, Martin Hulce, John M. Kum, Andrew K. Urick, Eric Villa

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Abstract

Exocyclic allene natural products and pharmaceutical agents are rare but interesting compounds: Fucoxanthin, grasshopper ketone, and analogues of prostacyclins, cephalosporins, antithrombic agents and sterol biosynthesis inhibitors are representative. Syntheses of exocyclic allenes commonly rely on extended conjugate additions to e.g., alk-2-en-4-ynones, syn SN2′-like additions to alkynyl oxiranes, and substitution reactions such as electrophilic substitutions of propargylic silanes. We report that the reaction of 3-alkynyl-2-cycloalkenones with 2 equiv of various hydridoaluminates but not hydridoborates proceeds via diastereoselective 1,4-reduction of a vinylogously propargylic intermediate alcoholate to provide exocyclic allenes as major products. Isomeric 3-alkynylcycloalkanols also are observed.

Original languageEnglish (US)
Pages (from-to)6052-6063
Number of pages12
JournalTetrahedron
Volume72
Issue number40
DOIs
Publication statusPublished - Oct 6 2016

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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