Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

• Rashmi Singh,
• Tomas Horsten,
• Rashmi Prakash,
• Swapan Dey and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 977–982, doi:10.3762/bjoc.17.79

• , Belgium 10.3762/bjoc.17.79 Abstract Several new heterocyclic systems based on a hydroxybenzofuro[2,3-b]pyridine building block were prepared. This benzofuropyridine is easily available from the Meerwein reaction of benzoquinone and a heterocyclic diazonium salt, followed by reduction and cyclization

• . Electrophilic substitution and further condensations give polycyclic systems, including oxazolo- and chromeno-fused analogues. Keywords: benzofuropyridines; benzoquinones; dibenzofurans; Meerwein reaction; metal-free synthesis; Introduction Dibenzofurans are important oxygen-containing heterocycles present in

• polycyclic derivatives was designed. The procedures towards such polycyclic building blocks include C–H-arylation strategies. In the classical Meerwein reaction, aryldiazonium salts are used as the reagents to couple aryl groups to electron-poor alkenes, and this process is assumed to proceed via a free

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• approaches thus arousing our interest [2]. In 2014 König reported a photo-Meerwein reaction between arenediazonium salts and styrenes to afford, upon intervention of the nitrile solvent and water, amides of formula 1 (Scheme 1) [3]. According to the proposed mechanism, the carbocationic intermediate A

• reaction mixtures during attempts to intercept the radical/cationic intermediate with various nucleophiles (solvents employed are reported). The meso-flow apparatus assembled in-house. The components are shown on the left, while the operating system is shown on the right. Photo-Meerwein reaction leading to