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Regioselective Anionic [3+2] Cyclizations of Isoxazole, Pyrazole and 1,2,4‐Triazole Dinucleophiles − Efficient Synthesis of 2,4‐Dihydroimidazo[4,5‐ b ]quinoxalines, 3 H ‐Imidazo[1,2‐ b ]pyrazoles and 5 H ‐Imidazo[2,1‐ c ][1,2,4]triazoles
Author(s) -
Langer Peter,
Wuckelt Jörg,
Döring Manfred,
Schreiner Peter R.,
Görls Helmar
Publication year - 2001
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 - 10.1002/1099-0690(200106)2001:12<2257::aid-ejoc2257>3.0.co;2-z
Subject(s) - chemistry , regioselectivity , isoxazole , pyrazole , stereochemistry , triazole , combinatorial chemistry , 1,2,4 triazole , medicinal chemistry , organic chemistry , catalysis
Regioselective cyclization reactions between oxaldiimidoyl dichlorides and 3‐aminopyrazole and 3‐amino‐1,2,4‐triazole provide convenient access to biologically relevant 3 H ‐imidazo[1,2‐ b ]pyrazoles and a 5 H ‐imidazo[2,1‐ c ][1,2,4]triazole. In contrast, treatment of 3‐aminoisoxazoles with diimidoyl dichlorides results in a new and efficient anionic domino process for the synthesis of biologically relevant 2,4‐dihydro‐1 H ‐imidazo[4,5‐ b ]quinoxalines. All cyclizations proceed with high regioselectivities, which are explained with the aid of semiempirical computations.