Photoinduced Synthesis of Dibenzofurans: Intramolecular and Intermolecular Comparative Methodologies

Abstract

The S1 reaction has been used as a powerful tool for the synthesis of heterocycles, and only a few studies about photoinduced intramolecular cyclization to generate a new C-O bond by a radical pathway have been reported. This work introduces two strategies for the synthesis of substituted dibenzofurans by electron transfer (eT) reactions. The first one is a three-step process that comprises bromination of o-arylphenols, Suzuki-Miyaura cross-coupling and photoinduced cyclization in order to obtain the above-mentioned products. The second one is a metal-free procedure and does not require any photocatalyst. Different solvents were tested, and the yields ranged from low to moderate. A comparison was established between both methodologies, showing that the second one is the most suitable for the synthesis of dibenzofurans.

Dibenzofuran Derivatives Inspired from Cercosporamide as Dual Inhibitors of Pim and CLK1 Kinases

“…The synthetic strategies to prepare dibenzofurans can be classified into two main categories [37][38][39][40][41] (Figure 2). One involves the construction of the dibenzofuran from the ring closure of diaryl ethers through C−C bond formation [37,38].…”

Catalyst‐Free Synthesis of O‐Heteroacenes by Ladderization of Fluorinated Oligophenylenes

“…Despite a large number of works aimed to develop facile incorporation of the furan ring, the principal synthetic strategies are not so numerous and break down into few categories depicted in Figure 1. The final step includes either transition metal‐catalyzed C−C coupling [22–26] or C−O bond creation, [17, 27–35] which is usually implemented via a two‐step deprotection/dehydration procedure [10, 14, , 18, 36–38] …”

Development of Titanium Dioxide-Supported Pd Catalysts for Ligand-Free Suzuki–Miyaura Coupling of Aryl Chlorides

“…Furthermore, 1a was reacted with 4'-, 3'-or 2'-methoxyphenylboronic acid (2c, 2d, or 2e) in moderate to good yields (3g, 3h, or 3i). The direct formation of heterobiaryl skeletons is important for the construction of partial scaffolds of biologically active compounds [66][67][68][69][70][71][72] and functional materials [73,74]. The coupling of 4'-chloroacetophenone (1a) with heteroarylboronic acid derivatives afforded the corresponding heterobiaryl derivatives (3j and 3k) in moderate to excellent yields.…”