Cu(I) Catalyst in DMF:  An Efficient Catalytic System for the Synthesis of Furans from 2-(1-Alkynyl)-2-alken-1-ones

Abstract

The cyclization of 2-(1-alkynyl)-2-alken-1-ones 1 proceeded very smoothly in the presence of alcohols 2 with a catalytic amount of Cu(I)Br in DMF at 80 degrees C, leading to the formation of highly substituted furans 3. The catalytic system reported herein is easy to handle, compared to the previously known system wherein the reaction between 1 and 2 needed to use moisture sensitive gold(III) chloride.

Cycloisomerization of 1,n‐Enynes: Challenging Metal‐Catalyzed Rearrangements and Mechanistic Insights

“…(187)]. [209] This reaction had previously been reported by Larock and co-workers, who used a gold catalyst. [169] The authors proposed here the use of inexpensive copper bromide in DMF at 80 8C.…”

Gold(III)‐ and Platinum(II)‐Catalyzed Domino Reaction Consisting of Heterocyclization and 1,2‐Migration: Efficient Synthesis of Highly Substituted 3(2H)‐Furanones

“…[6,7] This reaction is believed to proceed via oxonium ions. Based on this, we envisaged that alkynyl carbonyl compound 1 bearing a hydroxy group at the propargylic position might undergo a previously unknown transformation (Scheme 1).…”

Five‐Membered Heterocycles: Furan

“…Yamamoto has demonstrated that, in the presence of CuBr as a catalyst, trisubstituted furan 118 is formed from 117 and isopropanol (Scheme 6.49) [101], while Liu has shown that tetrasubstituted 3-iodofurans are afforded on employing similar starting materials and I 2 /K 3 PO 4 as reagents (see below) [102].…”