Base-Promoted Conversion of Propargylic Alcohols to 1,3-Enynes

Under acidic conditions, propargylic alcohols undergo Meyer-Schuster or Rupe rearrangements to afford two isomeric α,β-unsaturated ketones. Herein, we disclose a mechanistically distinct base-mediated regioselective conversion of TMS ethers of propargylic alcohols to 1,3-enynes in high yields with broad functional-group compatibility. Alternatively, trapping of the in situ-generated lithium acetylide with electrophiles enables access to functionalized internal 1,3-enynes. Owing to the ready accessibility of propargylic alcohols, this method provides a practical and attractive entry to synthetically valuable 1,3-enynes.