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Lewis Acid Catalyzed Reductive Cyclization of 2‐Aryloxybenzaldehydes and 2‐(Arylthio)benzaldehydes to Unsubstituted 9 H ‐Xanthenes and Thioxanthenes in Diisopropyl Ether
Author(s) -
Verma Shashi Kant,
Prajapati Anamika,
Saini Manoj Kumar,
Basak Ashok K.
Publication year - 2021
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202000836
Subject(s) - chemistry , benzaldehyde , diisopropyl ether , lewis acids and bases , medicinal chemistry , aryl , ether , reductive elimination , transfer hydrogenation , catalysis , hydride , organic chemistry , metal , alkyl , ruthenium
Readily accessible 2‐aryloxybenzaldehydes and 2‐(arylthio)benzaldehydes undergo a sequence of reactions leading to a wide variety of unsubstituted 9 H ‐xanthenes and thioxanthenes in high yields when heated with a Lewis acid in diisopropyl ether. This reductive cyclization method is compatible with several important functional groups. The method is also applicable for the selective reductive cyclization of the more electron‐rich aryl ring of a 2,6‐bis(aryloxy)benzaldehyde. The key feature of this transformation is the chemoselective reduction of a transient xanthylium ion in the presence of aldehydic group via intermolecular hydride transfer from diisopropyl ether (solvent).