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Lewis Acid‐Catalyzed Selective Synthesis of Diversely Substituted Indolo‐ and Pyrrolo[1,2‐ a ]quinoxalines and Quinoxalinones by Modified Pictet–Spengler Reaction
Author(s) -
Verma Akhilesh K.,
Jha Rajeev R.,
Sankar V. Kasi,
Aggarwal Trapti,
Singh Rajendra P.,
Chandra Ramesh
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201101013
Subject(s) - chemistry , benzotriazole , tetrahydrofuran , catalysis , tandem , lewis acids and bases , combinatorial chemistry , organic chemistry , pictet–spengler reaction , reaction conditions , cascade reaction , solvent , materials science , composite material
An efficient tandem process for the selective synthesis of 1,2‐annulated α‐fused quinoxalines using benzotriazole methodology by a modified Pictet–Spengler reaction is described. The approach involves the reaction of arylamines 4 with aromatic aldehydes 5 to furnish 6‐ endo‐dig ‐cyclized products. Dihydroquinoxalines 6 were selectively obtained by using AlCl 3 in tetrahydrofuran (THF) at room temperature for two hours. However, after ten hours, quinoxalines 7 were obtained exclusively in excellent yields. A series of biologically important fluoro‐ and piperazenyl‐substituted quinoxalines were also synthesized. This developed methodology also provides access to a novel tandem synthesis of quinoxalinones 9 .