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

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Propargylic alcohols typically rearrange to α,β-unsaturated ketones under acidic conditions (Meyer-Schuster or Rupe rearrangements).
• A need exists for alternative synthetic routes to 1,3-enynes, which are valuable synthetic intermediates.

Purpose of the Study:

• To develop a novel base-mediated method for the regioselective synthesis of 1,3-enynes.
• To explore the functional-group compatibility and scope of this new synthetic transformation.

Main Methods:

• Conversion of trimethylsilyl (TMS) ethers of propargylic alcohols using a base.
• Trapping of in situ-generated lithium acetylides with various electrophiles.

Main Results:

• High yields of 1,3-enynes were achieved through a base-mediated regioselective rearrangement.
• The method demonstrated broad functional-group compatibility.
• Functionalized internal 1,3-enynes were successfully synthesized via electrophilic trapping.

Conclusions:

• A novel and practical base-mediated method for synthesizing 1,3-enynes from readily accessible propargylic alcohols has been established.
• This approach offers an attractive alternative to existing methods for accessing synthetically valuable 1,3-enynes.