Thorpe–Ingold effect in copper(II)-catalyzed formal hydroalkoxylation–hydroarylation reaction of alkynols with indoles

✍ Scribed by Nitin T. Patil; Vivek S. Raut; Rahul D. Kavthe; Vaddu V.N. Reddy; P.V.K. Raju

• Book ID: 104096962
• Publisher: Elsevier Science
• Year: 2009
• Tongue: French
• Weight: 915 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2009.09.057

✦ Synopsis

The use of Cu(OTf) 2 as a catalyst for tandem hydroalkoxylation-hydroarylation reaction of alkynes tethered with hydroxyl group is reported. The reaction proceeds at 60 °C or even at room temperature with 5 mol % catalyst loading and produces C-3-substituted indoles in good to high yields. The method was shown to be applicable to a broad range of indoles, containing electron-withdrawing and electron-donating substituents, and alkynol substrates bearing sterically demanding substituents in the tether. Interestingly, it was found that Thorpe-Ingold effect is operating for this cyclization reaction. Easy availability and low cost of Cu(OTf) 2 make this method attractive and amenable for large-scale synthesis compared to known literature methods.